The big underlying factor is that so many software prices are artificially low because they're subsidized by collecting and making money off of users' personal data.

Unlike with physical goods, users don't know any "objective" ways to judge the fairness of software pricing. So they see (monetarily) free software everywhere and think that good software is cheap to make.

You can view the subscription/purchase debate as a second-order effect of people just not wanting to pay much for software, because they think that's what it's worth.