Well most recently this year i crossed US borders at the Texas point of entry. I was told expressly to always provide them with my devices, as if i said no thank you i would be denied entry to the US and it would go on the record for future visa applications, which could be denied on grounds of that, thus affecting future assignments. When you get a work visa, you have a time limit to enter the US and if you miss it, you need another. I was told i was completely responsible for any data that third parties could obtain and i would be fired and legally prosecuted if sensitive data was seen by people who did not have security clearance and NDA clearance for the data i was carrying, which border security does not have, even though some US government personnel do have those clearances.

Fortunately my company provided cloud space for any personal or company data i would be carrying and i wasn't asked for anything because i came from Europe and i guess they weren't too suspicious about me, so in the end it wasn't an issue. Nevertheless, i had to take mandatory corporate training to prepare for any immigration interviews and had to sign specific liability agreements for the data i carry since it is highly sensitive.

I don't just work as a liason in the US, but this was the most recent. For the industry i work in, this is pretty standard.

You can say no, but that doesn't mean there won't be consequences, in my case I'd lose my job or lose assignments, which would probably mean I'd be put only on European assignments or demoted to a domestic only position, which would be paid substantially less. So in essence, i can't really say no nor slack on opsec. Being able to feed my family is more important than protesting on grounds of principle for me. Also i could have issues getting to the US in the future, for any reason that may be, since getting a work visa requires grueling consulate interviews and they check literally everything. It's one of the most annoying places to get work visas to, even coming from Europe. It took me one year of scheduling and attending interviews to be cleared for it. I was even asked to provide all my personal social media account handles.