your ducking behind a rubbish bin or parked car continues to show just how different it is moving about unnoticed in an urban environment like that compared to a natural environment. Think for a second how you would react if you saw someone "duck behind a trash can or parked car" while going about your day.. that kinda thing gets attention because it's strange & kinda crazy. Walking on leaves rather than quietly through them is something to avoid in a forest because it's an out of place sound in a comparatively quiet place... a city is loud & noisy enough that someone walking across broken glass in the street or walkway is not noticeable from anywhere but very close... but someone walking funny because they are trying to silently step across broken glass is very out of place from very far away (ie football field or more).
In fairness, the stealth rules for hiding don't apply if if I see somebody duck behind a trash can. Presumably the were never hidden, or failed their Dexterity (Stealth) check and didn't hide before I saw them. I'd also suggest that if I were following somebody with the intent to be hidden, particularly at night, avoiding making my own noises would be worth doing. Those noises could be not brushing against things to ensure rats don't scurry out, or scare the flock of pigeons off a statue.
During the day in Times Square, sure that broken glass isn't to make any difference, but I still want to stay behind people and out of sight otherwise I'm going to get made. I'd also want to use my Dexterity (Stealth) to slip between the throngs of people so I don't get some German tourist yelling at me that I just spilled their Venti Mocha Latte on their new chinos.
Think about the way a perp gets tailed in a police procedural. The cops are following until the suspect notices the cop following them, then they switch out. The cop following still does their best to stay behind things and be unobtrusive, until they fail then they fall back and use Deception to make it seem like they're just some person out for the day. When the suspect bolts that Deception has failed because they realize something is up.
If we're concerned about urban versus natural environments lets look at it this way: the rogue can still sneak up on a Daask group doing a dirty deal in a back alley in the Cogs This presumably involves hiding above, under on top things to remain unseen, as well as not knocking things over to prevent giving away their position. And I think the same principles apply to allow a character in the Eldeen Reaches while stalking an owl bear.
The fact that td&d treats the two types of stealth the same leads to other problems like the druid who knows about every plant & animal in the forest including how to dress & skin a kill but can't even exhibit basic levels of hunter type stalking while stomping around looking for a deer to bag for camp or the fact that there are no skills that even kinda fit the sort of streetwise/social engineering/contacts/etc that apply to doing certain types of things in a city.
Deception or Intimidation seem like good places to start for proficiency applications if you're working on distractions.
If the druid wants to be stealthy they roll a Dexterity check, and apply an appropriate proficiency. They may or may not have a Stealth proficiency. Never mind that bagging a deer or whatever for food is covered by the Survival proficiency, not the Stealth proficiency.
Moving through a crowd unnoticed can be used with that, but again its about hiding behind and around things and people. Moving through a crowded market still requires the character to hide their presence in some way, either behind people or things. I think Assassin's Creed 2 did a reasonable job of showing how this can be done, particularly when blending in with a group.
