For context, I live in the UK but I've heard this is a lot more commonplace in the US.
I'm currently employed but my role is causing my brain to melt so I decided to see what's out there. I applied for an application support role (IT), went through primary and secondary interviews and felt that both went extremely well. However, right at the end of the second interview, they casually asked me if I was okay with drug & alcohol testing. I was so surprised by this question (having never been asked it before at interview stage) that I said yes, but upon reflection it just didn't sit right with me. It's none of a corporation's business what I do outside of work so long as I turn up sober (that's a given!) and complete the work to an acceptable standard.
I'd understand if the role involved the safety of others (driver, air traffic, machine operating etc) but for a desk job? Really? Nah, seeya.