Would you be willing to relocate to an as-yet undisclosed location?

Every interview process is exhaustive, and one way to determine a good fit is by determining how familiar a qualified candidate is with the company or the position. To find the best candidates for any position and where they'd complement their team, the interviewers need to evaluate how well the needs of their company and the needs of their employees align.

If you're willing to travel for work or have in the past, volunteer it. If you're not open to traveling, don't say no. If you weren't aware travel was a prerequisite for the position, ask if it is. Tell them you're interested in the position and that you'd be open to discussing it further, but your understanding of what constant business travel looks like may not complement your current lifestyle. Ask more questions about the position, be flexible, and be open to negotiation. There may be room for advancement from within, for which a willingness to travel may be a prerequisite.