I get a lot of that also.
One ride I helped a disabled kid into/out of my car. Packed his wheelchair in the back of my SUV. His mom was real nice and tipped me $5 but that kid...never even said thanks for the help. I told him to have a good day and he looked the other way.
It's not my job to help someone into my car. Lyft has a platform specific to that need but it can be hard to get because not many drivers qualify for that. Mom appreciated the help even if that angry bastard she calls a son didn't.
Maybe it's new to him and he's embarrassed about it or depressed. Honestly, if you help someone out expecting something out of it, then you really did it for yourself. I'm not trying to give you a hard time about it. I've had the Same attitude about stuff like that, but I try to remind myself that I don't know what kind of shit people are going through.