In the software engineering industry, it's very often that the final stage of the interview is an onsite in California, where you spend a minimum of 3.5h doing the interviews; expenses are normally paid, but your time itself isn't normally compensated.
It is not uncommon to have 6h to 8h of back-to-back interviews, which are normally interrupted only for lunch, which itself is often on-site without leaving the potential place of employment, and in SF Bay Area, you're almost always accompanied for the lunch as well.
If a single non-exempt employee would happen to interviews you for 3.5h (e.g., for a simulation of an actual work day using XP pair programming methodology, which is strangely rare), they'd be legally entitled for a 10-minute break themselves, hence, you'll very likely get a proper uninterrupted 15 minute break as well:
Employers must authorize and permit uninterrupted rest breaks for all nonexempt employees whose total daily work time is at least 3.5 hours. These mandatory rest breaks must be offered at the rate of 10 minutes for every four hours worked, or "major fraction" thereof. Anything over two hours is considered by the courts to be a "major fraction" of four.
However, outside of pair programming, you often get a different person for each hour of the onsite. These folks manage their own breaks on their own time, whereas you the interviewee have a fixed schedule, and usually don't get any official uninterrupted breaks in the schedule for the whole 6 to 8 hours of the onsite. Is that legal?