I delivered for Dominoes back when they did the $4 off if it didn't arrive within 30 minutes. The town I worked in had all income levels.
If it was a lower income area it was a mixed bag.
I loved delivery to young singles apartments, families starting out, etc. they generally tipped well, they weren't making a lot of money but they were people who were WORKING and understood how hard it was to make a buck. Especially the singles apartments, but that was mainly because more than once a drunk/stoned naked woman would show up at the door!
Then there were the "established" poor areas where poverty was a lifestyle. They would turn off their lights, park a car in front of the mailbox or give the neighbors address. Anything to try to delay the delivery past 30 minutes, and they would let you know if you were 1 minute late! Not only no tip, but $4 off the pizza!
For middle class, upper middle class, affluent, it was also mixed bag. Some tipped well, others didn't.
Like poverty, the other income groups weren't defined by their income but by their values. Some tipped well, others didn't. But I will say this, I never feared for my safety in the middle class and nicer neighborhoods, but there were some poverty areas most drivers including me liked to avoid due to safety concerns, and one section 8 housing complex our store would not deliver to due to the number of robberies.
For a guy in his early twenties it was a fun job, and I made decent money all things considered - but I wouldn't want to do it now because I'm not that fit! If you have a reliable compact car with good mileage, it is a decent way to bring in a few bucks, but compared to the 1980s it's probably not as good. A large pizza back then was about $16, they tend to cost less now!