Nice and fun idle game.
I found the balance to be a little out of whack though.
The speed upgrades with their nearly factor-of-ten improvement to profitability are much better than anything else. In a similar vein, the scaling between food and drink appears to be vastly off. Food costs (at least in the midgame around the one-star mark) almost ten times as much to upgrade as drink, yet it's worth the same per customer.
Also, I agree with shadow that the implied time pressure or the story could have been worked in a little more into the mechanics themselves.
Maybe something like the player needing to identify "seedy customers", which'd give the player also a little bit more interaction with the game (since, especially once all shop items are bought, it's a bit too idly).
Nonetheless, I quite enjoyed playing the game, good job!