Yeah I'm stuck in the way table-top D&D combat is resolved. Your also stuck in it.
Only as stuck as I allow myself to become.
Games can't be resolved that way unless you break down the actions into smaller actions thus the logic of using rounds/turns based on small amounts of time.
Let's go back to your example of someone riding a horse through a gate and lighting a pipe before anyone else could do anything, which you (quite rightly) said was absurd; and compare it to another example which I actually saw in a 3e game and to me is equally absurd:
Two PCs, one has had silence cast on himself, restricted visibility due to fog, two different but interacting battles going on (half the party involved in one, half in the other, about 100' apart), both PCs want to move quickly under cover of that silence from one battle to the other and catch the enemy there off guard. (both are in heavy armour, thus the need for the silence spell)
We're in a combat, thus in turn-based mode. Character with silence's init. comes up, he holds until other character's init. so they can move together. So both init's come up...but turn rules say one character has to move at a time; simultaneous actions cannot occur. End result: the second character could not remain in the silence while moving - either it ran away from him (silenced PC acted first), or he ran away from it (non-silenced PC acted first). Absurd.
Now it's easy to say the DM here should have just let them move together...but the bigger issue remains: hard-wired turn-based thinking does not allow for simultaneous actions regardless how long the round is, leading to some rather ridiculous situations like this.
Sadly, it also does not allow in any way for two (or more) foes to kill each other at the same time.
So basically you break down the game into smaller chucks within a minute and imagine smaller rounds in your head but you won't admit it because you want to have rounds be longer such as minute . It's sane practice just to admit shorter rounds. I did.
I'm willing to abstract it a bit more, perhaps. I'm not trying to track every swing of every weapon; the to-hit roll is more an indicator of how well you're doing over the length of that round, however long it may be. That said, many things - usually involving spellcasting and attempts to interrupt such - do get broken down into fractions of rounds; that's what segments are for.
Much easier and logical to break down turns taken by players, NPCs, and creatures into shorter rounds. If you going to have to negotiate it all in your head, then just do in the game. In other words people who claim they are playing 1 minute rounds are actually not. Your playing, based on what you are saying, a large meta-round with a whole bunch of true rounds within that meta-round.
A whole bunch of segments within each round, perhaps...but nowhere near as combersome to play through.
And to clarify: we re-roll initiative each round, again because robotic I swing-you swing-she casts-monster bites-I swing-you swing (repeat) is utterly unrealistic; re-rolling makes it at least a bit less so. Combat is chaotic, and you never know when you'll get your best opportunity to do whatever it is you're trying to do. We use an unmodified* d6 for init., which means of course lots of things will inevitably be simultaneous. This is fine, if you get killed on a '5' and your initiative was a '5' you'll still get your swing in and may kill your assailant at the same time. Etc.
* - very rare items or effects exist that may trump this.
Lan-"always watch out for that last dying strike"-efan