Subform is in beta, and the others are finished and offer free trials.
Also, Figma and Framer are backed by venture capital. They're going for marketshare and don't need to make any money from licenses. I appreciate that the Subform authors are upfront about their position on the order page: they're two people who need to make a living, and you can choose to support that or go elsewhere.
The cost of subform is truly on the higher side. I understand that it's catered to a niche target group - how niche is it though? if it's managed by 2 people, 1000 customers would bring in $25.000 monthly before tax. I cannot imagine that they aim for 1000 customers only, though.
I tried — and failed — to make a living in this market with two products, Neonto Studio [1] and React Studio [2]. Reaching one thousand subscribers was a distant dream. Nowadays we just give away the base product, and the real business is focused purely on customizing the software for enterprise in-house development where the pain is much greater than with what one might call "competent teams" (i.e. practically anyone reading HN).
[1] http://neonto.com/nativestudio [2] https://reactstudio.com
[1] https://www.sketchapp.com/
[2] https://www.figma.com/
[3] https://framer.com/