That's the "I could implement dropbox with sftp and rsync in an afternoon" response. It's nice not to have to, and people can be forgiven for exchanging money for time.
It’s $10, so they’re clearly also not unaware of the effort needed to support software. It’s fine for different people to have different takes on a common concept and let the market sort it out.
I have the skills to build it myself from source and sideload (mostly dealing with Apple's obnoxious code signing certificate infrastructure), but will gladly pay the $10 to fund the development. Too bad the iOS version of UTM is not available on the iOS App Store and forces sideloading. I might get around to installing it on my iPad one day (there is the excellent QEMU-based iSH on the App Store, however).