I work for AAA. 95% of the time the person coming to tow your vehicle does NOT work for AAA. They are a contractor, they work for a tow yard. While they do appreciate tips, they are definitely not expected. Dont feel bad if you dont have the money or cant afford to, but if you feel like he did a good job, go for it.
And just a "tip", they service people just like a triage system, the person in the most danger gets service first. Someone stuck in the middle of the freeway is going to get service before the person who has a dead battery at home. Sometimes They will tell you 2 hours before you can expect a tow, and then a rush of very serious calls come in and your 2 hours becomes 3, its not the drivers fault, there are only so many tow truck drivers in any city at one time, and almost all of them work with AAA, if you have to wait longer its because someone in more danger needed service first, i know it still stinks to have to wait, but its in the interest of safety and getting people in danger out of harms way.