AT&T DSL customers get a limited number of dialup hours. IIRC it is for being on the road - though I have never used mine, since all the places I go have broadband. I doubt there would be enough hours offered to be useful.
I don’t think the issue here is denial that the problem might be undetectable by a remote tech, but the refusal of the tech, as far as I can tell, to consider this a possibility. I don’t think the techs are stupid, necessarily, but the scripts are designed to treat the customer as if he or she were stupid, and in my experience the conversation breaks down when the customer isn’t. I’ll admit that in the majority of cases the customer is stupid or clueless.
I make an exception for DishNetwork. The last time I had a problem I got an automated troubleshooting system on the phone, which let me fast forward past things I already tried. It eventually got to telling me how to reboot the receiver, which worked. Even better someone got on the phone after I sat there for a moment as the channel guide reloaded, to see if I was having problems. I kind of think that low level techs who just follow scripts are going to find themselves automated out of a job, because having a computer do it is even cheaper than sending the call to India.
I’ve already got dialup from Earthlink. And it will now be rolled into my cable internet bill as a free add-on. (Don’t use it very often but I’m glad it’s still out there).