Like others have mentioned, I tip for better than just the typical service, and how much better determines how much tip. For example, if I go to a coffee shop and they just pour a coffee, they don't need a tip. It's not like they're going out of the way to make that coffee, that was their job. But, if I go to the same coffee shop regularly, and the person working there remembers my order and is getting it ready as I'm walking up to the counter, or I have special requests that they fill for me even though it's not on the standard menu, then they get a generous tip.
As for garbage collectors, I've never tipped them. I'm not even sure how you tip them since I never see them. I don't even know if it's the same person every week. HOWEVER, back in the days when I wasn't paying for trash collection and they took whatever was put out (now I have to pay to have trash collected, and am limited to only two cans of trash or I pay extra...everyone gets the BIG cans), if I put out a HUGE amount of trash, such as when cleaning up the yard or basement or some such, THEN I'd be out at the curb on the day of trash pickup when I saw the truck pull up and made sure that crew got a tip for taking all the extra trash. That was expecting more of them than the usual household trash pick-up, so deserved a tip.
Oh, NYC is ridiculous though! If you live in a building there, they give you the list of all the employees who should be tipped.

My boyfriend went through that last year. He didn't even know who half the people on the list are. I can understand tipping the doorman and concierge, and maybe a few folks on the maintenance staff if they did work for you, but when you don't even know who the people are, meaning you've had no contact with them at all, why should you tip them? But, if you don't and you need them the next year, they hold a grudge and don't help so much...even though THAT should be the year they would then get a tip for then being helpful. That is out-of-control tipping.
Wow, fileen, that was some experience! He had the nerve to ask why he wasn't tipped? I'd have told him he was lucky I didn't get him fired by making a big fuss in front of the whole restaurant and manager, and my tip to him was that he should get a clue.