Shared laundry may be unavoidable depending on the size of the home;   if the ADU is a smaller one is probably a safe move to make laundry free but if you are considering a large (2 or 3br) ADU you might want to think about metered laundry (coin op or something) just in case you get an occupancy-limit sized household.I don't know if they would allow it for an ADU vs. a real duplex,  but the ability to add a second electric meter and breaker panel would be a good way to prevent issues with excess utility usage (you could bill back or just require tenant to get the electric service in their name) - even without that there are submetering options.