It really depends on the lab, I think. When bulk loading XP2, I got my cassettes back from some labs, and not from others. When I could expect not to get them back, I tried to re-use normal disposable metal canisters. Reusing them once is fine. I could get them from a minilab if I didn't have spares.
That was in Germany. Here and nowadays I have C41 processed and scanned only at a minilab (development + scan for about $1...), no problem there.