Support includes things like "I paid and my account doesn't work". In addition, you simply can't provide a good service without support. Being able to answer questions like "I'm trying to do X with your tool, how do I do it?" leads to better customer engagement and retention. It's part of the cost of doing business. The marginal benefit of doing that to microrevenue customers is not worth it financially, and as a result, you will never get as good of engagement nor retention from them.

One of the strengths of small business over a big co like Google is your support is NOT automated and you take the time and care to talk to and answer your customer's questions. You can't do that when you charge 10 cents a customer

On top of that, you still need to market/advertise to those users.

It's less time consuming, causes less friction, and is more profitable to just charge $10 dollars instead