As someone who has previously worked on real time audio apps on Mac, I find the price justified.

Supporting MacOS with anything that needs kernel drivers requires constant updates and the potential market is so small that it kind of needs to be expensive per customer or else you need to cut corners with the quality.

Windows has 5x the market share, so there you can sell for 80% less per user because you'll sell more licenses which compensates that. And a windows version for $2 per month sounds fair, so then $10 monthly on Mac is fair, too.