Leetcode is used by many companies for interviews and whiteboards. For example when I interviewed at Facebook the first screening problems were from the site and the later whiteboard problems for the on-site interview were as well.

I have no experience working with software "at scale" so it may be that my interviewing experiences are different from yours. Generally speaking, though, software developers at non-tech companies, or at agencies for small-med business clients (what I tend to work for) don't ask those kinds of technical questions.