I only have one rest area I frequently pass. It is closed..
They can be closed for several reasons.
One is natural.. I recall a Rest area in MI that was closed for a period because a well driller hit a pocket of natural gas and it got into the ground and spread, Several houses went for a flight as the gas went BOOM and the rest area was in the affected area. Clearly closing it was the only safe option till the gas was dealt with.
Money (Politics) is yet another reason.. No comment.
Vandals are yet another reason.. They can clog the plumbing
And finally, natural "Disaster" can also clog the plumbing.. Now I've not seen that in a rest area. but I did see it in a campground.. The laundry and primary "Facilities" clogged.. The manager called Roto-Rooter and the sewer line was full of gravel, they cleared it and he suspected vandals.. (I disagreed, hauling all that gravel to the toilet is more work than most Vandals will do).l. Sure enough when it happened again they sent a camera for a swim and found the sewer line had rusted out and here comes the gravel.. Major repair job