MAT definitely gets demonized in some sectors ("trading one addiction for another" re: methadone, etc). While most physicians have a better understanding of it than the general public, there's still a fair amount of stigma around it and a trend to just counsel patients "don't do drugs" (lol) rather than considering MAT (despite the evidence that it's the best option to actually prevent overdose deaths). There's also just a general lack of knowledge about MAT - what the options are, how to prescribe/refer, etc. And since some of the options require a special waiver to prescribe, patients often can't find a provider who is able to prescribe it.
I've been heavily involved in harm reduction in med school, and while there are some amazing physicians we work with, it's also very disappointing to see how horribly people who use drugs are treated by the medical system. Doctors, nurses, etc can say and do some really awful things and some of the stories i've heard are heartbreaking.