We're in the camp that prefers getting two weeks' of laundry done in 1-1/2 hours at the laudramat and be done with it. When folks say they throw a load in their RV one daily I just can't imagine doing that. I don't want to think about laundry daily.
We also used public parks as our first choice so there were no hookups. Using a washer/dryer was impossible.
We full-timed for 16 years without one and honestly, NEVER, found a laundry that was dirty. We used the ones in town and there were attendents cleaning them after use. We did other errands while waiting our 1-1/2 hr. - no time lost. Everyone is different, for sure.
OP: As you're looking at RVs, there is usually a big hall closet. Look carefully in it and you'll probably see the washer connections in there were plumbed.