Depends on what else you need to service your clients. Some types of consulting require flights, hotels, dinners, equipment, et c.

I never had travel or meals I didn't bill to a client, no. Negotiate better. ;)

I work with small companies.

Some clients prefer a simple bill and clear mental model of the costs. I make (slightly) more money on the bills in which I don’t break out my expenses than the ones that I do.