(Sorry, this turned into a rambling manifesto.)
I would even be willing to pay more than $50 per month per developer (editor).
Maybe a sliding scale where for $50/developer gets you up to five $20 users, $500/developer gets you up to fifty $20 users and so on.
Let's be real, most, even micro businesses can afford $50 per user per month for important business tools. The problem is you add Retool, plus Quickbooks, plus CMS, plus, plus, plus and pretty soon you are taking a lot of money per employee. The SaaS model is a cruel mistress!
Companies manage this my only having two Quickbooks seats, one person manages mailing lists and so on. This can be done with Retool, but it is such a broad platform that eventually every user will find some use for it, even if it's only 4 times per month. I guess login sharing works there
Some companies (I have one I am working with now) use a lot contractors, all of whom need access to the backend, but only account for some hundreds in revenue each per month. She can't pay $50 per head for them. She can easily pay $50 each for the 8 core employees.