Kansas, wheelchairs (and the people who use them), are visible in Puerto Vallarta in a way that they aren't always back here in the USA. It's one of the many reasons we fell in love with Puerto Vallarta, because people who live there are so helpful.
Our very first trip, it was such a shock to not be invisible (our standard joke when we are vacationing somewhere that is not Mexico and get ready to head out of the day is that we should go rob a bank, as no one would ever see us!) :) In Mexico, we are most definitely "seen."
In fact, on our trip back home, my spouse had parked me in the Memphis airport next to some kiosk while he ran to the bathroom. I was sitting there waiting for him when a guy in a suit talking on his cell phone walked smack into me, cursed me out and kept on walking. Welcome back to the good old USA! :)
If you are using a wheelchair in Mexico, you need to accept that you are not going to be in control of the accessibility. I've been picked up and slung over someone's shoulder, carried by two guys on either side of me and transferred to a regular chair and lifted up the steps.
Oh, and for the original poster...make sure that the wheelchair your daughter rents has flip up and cut out arm rests...not the locked in place or pull them out kind (the medical equipment people will know the difference). If you get the kind that are on a standard, heavy rental wheelchair, she will be sitting way back from every table she eats at, balancing her plate in her lap.
Most of the tables in Mexico have a lip just underneath the tabletop, which makes it impossible for the wheelchair to fit right up underneath it. Flip up arms are a godsend when that happens. For tables that don't have that lip, the cut out arms make it possible to slide the wheelchair right up to the table, which isn't possible with the fixed arms type.