@HerMammy
That's just enabling him/her to rely on you, and not grow up. It shouldn't all be on you the parents.
My DS 24 is non-verbal autistic, I see him probably twice a month. But, when I am not up to the approx 1hr of crap traffic, they bring him to me, 1 bus and a train journey, which he loves.
It's about building independence, a 20 year old, should be able to visit their parents, without being picked up.
If, they went to university, I would expect the same, except when taking stuff to campus and back. If we are looking at personal examples, I happily undertook 6 hrs journeys cross-country to mine, without my parents, as well as to see the boyfriend.
We need to know when to foster independence in our children/teens, even the disabled ones, otherwise, they won't become proper adults.
If she isn't happy, it's up to her to say so and change her situation e.g. learn to drive, phone or WhatsApp more often. But, she can't expect her Mum, to be her taxi.