Here's an interesting perspective:
Let's say the average survey takes 30 seconds to fill out with an average payment of $0.15. That works out to $18/hr if you were doing surveys the entire time. How are those earnings somehow less valuable than $18/hr at a job? Sure, you can only spend them in the play store, but they still took work to earn and they hold equal dollar value.
Btw, the reason a grocery store wouldn't take back food is more to do with health codes than anything. If it's general merchandise, many stores do accept unconditional returns or exchanges within certain time frames.
Your my hero Mooncatt!