I'm not from the US so maybe that's grounds for the different expectations. And I'm not sure if my employer would actually be breaking any laws snooping on the laptop; I certainly hope so.
I'm not sure what the situation is in the US, but here email is given the same legal status on secrecy of correspondence as old-school snail mail has. There is a way for employer to legally read emails in case of e.g. espionage suspicions, but that requires a note and follow-up with a public privacy official.
(I do like the required notifications through HR, but it doesn't sound like that is a prerequisite to ask permission, even in more privacy-stringent places)
For instance, many years ago I was Unix sysadmin and needed to get some work done on a machine using information that been emailed to one of my colleagues. Normally I would have just given the work to him but he was on holiday and this was urgent. The information needed was in his email but I couldn't just ransack his email. I had to ask the admin of the email system to open up that account and find the relevant email for me and copy that information. The admin in turn had to notify HR that he was doing this and justify it.
Generally all this works perfectly well.