And as an employee that actually exists in 2021, I'd tell you to get a clue.
>As an employee I prefer not to use the corporate network for truly personal email.
And that's your preference. If you think everyone shares that preference or even realizes the implications you're delusional.
>If I am the employer that responsibly monitors the traffic to and from our network, including TLS traffic, an employee that uses our network for personal use with a surveillance "tech" company service such as Google Mail, Facebook, etc. is putting her own privacy at risk.
No, you're putting them at risk by MITMing their traffic. There's absolutely nothing that forces you to do that. If you don't have separation between the network where humans live, and where The Business lives, that's what's irresponsible.