Then, the proxy makes its certificate available to users, you download it, and add it to your CA certs via the UI that browsers provide for that; HTTPS magically appears to work again.
HTTPS shouldn't magically appear to 'work' again, considering it is completely broken when a forced mitm is introduced.
If you want privacy against the administrators of your employer, don't use your employer's network to do things that need privacy.
The problem isn't necessarily what the employer sees, it's what the might employer keep around.
But even if reasonable people could disagree about that policy decision: the reality is that people operating large corporate networks require the ability to control SSL/TLS sessions; for instance, there are whole industry verticals where accessing a private email server not controlled by your employer is grounds for automatic termination, because regulations require them to track and archive email messages.
Finally, and I'm repeating myself: I am describing the reality of most Fortune-500 enterprise networks. In most corporate networks, you cannot simply talk from your desktop out to the Internet; you are required to use a proxy. You're also almost certainly on an 10/8 IP address.
In which case I end up shit creek without a paddle because there's no way to temporarily disable the security feature.
And I do not have control over the Proxy server because I'm not in the fucking security team.