You’d be surprised what a pair of coveralls and a ladder will do in lieu of a security clearance 😉
Indeed. My dad used to do sales/installs and when doing a quotation in a prison, he wasn’t subjected to a lot of the regular restrictions (since he needed tools for measuring and such). He was allowed to walk right in, no questions asked, with a bunch of stuff that prisoners could have potentially used to get themselves out of jail. When you look like you have a job to do, no one’s going to stop and ask what you’re doing.