To solve that problem Tesla recently introduced a Supercharger idle fee
https://www.tesla.com/blog/improving-supercharger-availabili...
Paying $10 for an extra 20 mins to finish their coffee may be worth it to someone in a $100k Model S, less likely for a $40k Model 3...
For example: Your battery charges in 30 minutes, but you stay at the station for an hour (30 minutes of charging + 30 minutes of idling). Next time you go to a charging station you get penalized for a certain amount of time (percentage of you idle time). Of course, this will probably never happen, but it would get the point across!