I've gotten large bonuses for Five Guys, but have never been paid $50 for one. I can't answer your question definitively, but I'm guessing that's just out of the ballpark for them. I don't think they're that desperate. They do look to see how far the shop is from you, but they're probably calling shoppers who live closer to see if they can get it done for less.
There are two shops in my area that I do on a fairly regular basis. Both were bonused way up (to the same fee) for the balance of December and were also on make an offer. I put in an offer for $2 over the (new) base fee for the one nearest me, and it was declined, even though I'd gotten that much for that shop before. I probably would have gotten it had I offered $1 more. Then I put in an offer for the one that's significantly farther, for $6 over the new base, and it was accepted. But I'm betting that if I'd gone even $1 higher, they'd have declined. You kind of have to keep track of what they accept and what they decline, and also not assume that because you got $XX for a certain location that they'll give you that again. I think some folks develop an intuition about these shops and figure out just how much more to ask and not be turned down!
I learn something new every day, but not everyday!
I've learned to never trust spell-check or my phone's auto-fill feature.