Will they ever lighten up and allow people with musical talent to entertain guests outside? Or perhaps will they adjust their sour attitude when a musician comes by and starts plucking a banjo, making people happy?

No matter what store, there are many shoppers who find that type of self expression "art" a little unsettling as they think they are going to be asked for money.... so they places store complaint. The better question to my fresh basket would be if during the summer would they allow a type of open mic night for musicians.

All very good answers guy's way to be supportive.

It's realy not a good location for entertainment. Inside perhaps. The farmers markets seem like the best avenue to go down

Although that's a wonderful thought, I don't feel a grocery store is the appropriate place for a music concert especially if your working towards tips.

That's not a good location, it seems it's kinda out of the way. I think you would have better luck with River Park Square

Some people don't enjoy certain types of music or any at all

I apologise this is happening. The only "advice" i can offer is call the business and or the owner and see if you can work out an agreement. I know Kendall Yards has a farmers market on Wednesday's, maybe you could leverage that into the deal. Hopefully you get to entertain soon!