I don't know that I would go so far as to say 'no one' regards it as railroading. Probably someone out there is going, "I protest. My character would never hang around in a tavern.", and a negotiation would ensue as to what the realistic place for the player to begin play would actually be according to the player's desires and the approved background of the character. Part of the problem I had with your early reference to 'You all start in a tavern' is that in fact, for 'purist-for-system simulationism' there is this prior to game negotiation over the simulations starting state where the DM and the players negotiate over how the characters will fit into the world at the moment that the game clock begins running and the whole elaborate mechanical clockwork begins to turn. Most true 'purist-for-system simulationist' DMs probably actually do feel that 'You all start in a tavern' is the first step to railroading the players. What if the players would rather start in a rowboat? What about on a pilgrimage? The DM is expected to kick off the game in a game state that represents what realistically would have happened before, where 'before' is something that the player has some input over and 'after' is also something that the player has some input over.
You pre-empted me. I was musing along just those lines.
Also, within the character creation process itself and creating of the backstory and the base premises upon which the adventure rests.
Your player wants to have a backstory which effectively means (s)he's extremely well connected and has lots of reserves upon which to call. The GM decides that this would detract from the overall gaming of the party (other player characters) at large and says no. Player cries "foul".
In my own particular campaign, I've shamelessly "scene framed" hard. I've created the situation in such a that all the players are on a level playing field - equally on the back foot - to ensure they all have to role play (and choose paths) to find their footing.
Where are they? How did they get there? How much do they know of the place? What resources do they have? How did they all meet? Did they know one another prior to the adventure? Why did/would they choose to work together?
I shamelessly took all of this away from the players' decisions in the interests of building a team in an interesting situation so they, the players, could role play.
I've had my fill of players that want their characters to be the favoured offspring of a major gang leader (one previous player actually used the term "Nomad Princess" to describe her character and expected that she'd have a
large nomad pack with medics, fighters etc at her beck and call because daddy's the wise and respected leader. Say what?)
You want resources in this game? Find 'em. Make the contacts. Role play getting them.
So, the characters' backstories all account for them having their particular skills, attributes, talents and equipment.
The "scene framing" has them all fairly recently leaving their previous employment. They are all strangers to one another with one contact in common... an employment broker. That broker receives a "laundry list" from a client in Australia and assembles the team based on their skills etc.
They then fly to Australia to meet their new boss. They have no local knowledge of the town they arrive in. They have no contacts there, no networks, no bolt holes, no family/gang/organisation. They have each other because they were thrown together and they are expected to work - whether or not they get along (the
players can decide if their character likes the others or not).
The lack of player choice is rampant in the initial set up - the players know it and I've explained why. They all seem quite happy with the fact that there's a ready-made reason why their characters are as "lost" in the environment as they, the players, are and that they can role play finding things out without stepping out of character - don't know how to get to the Qwik-E Mart on Lustbader St or what they sell out the back door? That's fine, you're new in town. They are happy with the fact that no one is at an advantage over the others, and they are enjoying the added challenge of finding their feet and choosing a network from amongst the NPCs I've provided (quite a large number already and I keep coming up with new ones).
They did not meet in a tavern and "decide" for
some inexplicable reason that they are going to trust one another and go adventuring. They were hired and
have to work together - "trust" is something they are going to have to role play at building.
Celebrim's point is bang on the mark. "Player choice" is often lost long before the game commences.
I'd argue that it's not always a Bad Thing. Not if the aim is to curb powergamers or munchkins and ensure the players are on an equal footing and/or to ensure there's better opportunity to role play in the session.
The game is for them all to enjoy - it's not the
Joe Bloggs Show with the other players there to provide sidekicks and comic relief for one munchkin.
I've made the set up in such a way as to give all the players the same opportunity for even more choices in game. Want to be affiliated with a major gang? Sure, take your pick - there's around 30 to choose from - make your moves and get connected. Want to have the CEO of a major corp in your pocket? You work out how to do it and it's yours. Want a couple of close friends you can rely on to watch your back? There's plenty to choose from.
Want some adventures/extra money outside work? There's plenty of that going, too, if you're up for it. Rather sit at the pub? Irish Tavern, Dinkum Aussie Boozer or ersatz Biergarten?
I've spent ages coming up with NPCs with their own stories and goals and personalities, news threads, ongoing mysteries and plots - plenty of scope for the players to bury themselves as deep as they like and take whatever side roads take their fancy.
And I've built in scope for the players to choose how they execute the jobs their employer gives them - they are "expected to have a degree of autonomy and work things out for themselves", so while the broad strokes might be "pick up parcel from here and deliver to there" the actual picture is up to them.