Absolutely valid, especially if mobility is a concern. But, similar motions and concerns would be present for a train and to a lesser extent, a plane.

I respect that many Americans may not be familiar with coaches in the US, and so often, they may not be available. Sometimes they are not in Europe either. I remember a particularly screamy bus driver from Dubrovnik to Montenegro because a passenger wanted the toilet 30 minutes in to our ride and there was no toilet available. She had to run to one at the border crossing. It's a good thing she did, our border crossing took over an hour to get through.

It can be very different. I just took two long haul buses in the Baltics (Lux Express) that had bathrooms and they were actually down steps as if you were getting off the bus. So you were on steps as the bus was moving opening the door and stepping down into the bathroom. So if mobility was an issue this could be difficult. Not sure this is the issue here of course but not all bus bathrooms are the same.

pepperment,
I've just checked Renfe for your departure on Sept. 7 to Bilbao.
The fares for the 7:52 am ALVIA have been loaded.
The ride takes 4 hours, 32 min.(the fastest ride of the day).
The train departs from Madrid's Chamartin Campoamor station in northern Madrid.

The fare in an Elige Confort XL seat, in a "preferente" car with 2+1 seat configuration, is 49.1 euros.
This Alvia train offers a bar/cafeteria car for purchasing food and drink, a rolling beverage cart (payment with c.c. only) and of course, toilets.
This ticket, the Elige Confort ticket (the most expensive fare) can be changed once without penalty.


This is the post that you read on the RS forum about a "ramp" access to an Alsa bus toilet.

"There are WC on the bus and yes by the back door which is in the middle of the bus. Hard to find as you can not really see the door, but it is on the ramp out of the door. I was not able to find it until I saw somebody use it.”

The poster, however, did not indicate that this was the "luxury" SUPRA service bus that operates between Madrid's airport and Bilbao. Alsa has several types of buses.

This comment was made in 2022 on a thread regarding bus service between Sevilla and Granada a route also operated by the ALSA bus company, but on that route Alsa does not offer Supra service, as it's a journey of 3 hours.