On the "cashless" at the ballpark....I went to Fenway Park a few weeks back, which also says it's "cashless" - which it is...at the concession stands, team store, etc.
The vendors walking around all took (and appeared to prefer) cash, though.
The cashless thing at the concession stands was to a fault...at the game, my son wanted a fried dough, so I handed him $20 and he headed off. He came back a little while later with a fried dough...and my $20. Apparently the concession stand had no ability to take cash, and as a 12 year old he didn't have a credit card on him. So, they just gave him the fried dough and told him next time bring dad.
So, with literally no way to accept money, they ended up just giving the product away. Crazy!