The "Install launcher for all users" option on the front page of the installer should be updated to read "Install py.exe launcher for all users" to reduce confusion.

However, we should also consider disabling this by default, so that the normal settings do not require admin privileges to install.

The reason we started with it enabled by default is because we had to stomp on the 3.4 and earlier py.exe, since there was no other way to make sure it wasn't an issue. That problem still remains, which likely means that if we detect an all-users launcher from a previous version we need to keep the option enabled, but at least for clean installs of 3.10 we can avoid the need for admin completely.

Follow up thought: we could switch out the front page checkbox for "Upgrade existing py.exe launcher (recommended)" when we detect an existing per-machine install, and hide it entirely if we don't detect it. So at least non-admin users have an easy way to bypass the admin requirement.

> but at least for clean installs of 3.10 we can avoid the need 
> for admin completely

Except updating PATHEXT always requires admin access. I do this manually by setting a user PATHEXT variable with %PATHEXT% as the first item and append the extensions that I need. This is okay because the system environment gets populated before the user environment, and a system environment that doesn't define PATHEXT is improperly configured. I don't know whether WiX/MSI can support this, but it's probably not worth the hassle and potential problems.