40,000+ employees. Travel 14 + days a month. Airfare and hotels booked through Concur ( Hotels usually at higher rates than can be found elsewhere). Can use either company issued MC or personal card with reimbursement. I would love to put my expenses on my DL Amex, but I frankly don't trust them to provide timely reimbursement. Flat $50 M&I per diem regardless of location, no receipts needed for that.

This has evolved over the 12 years of being acquired by ever bigger corporations. Per diem used to be $55 Conus, $110 Oconus. For about a year we had to put meals on the company card with receipts and no alcohol. That was no good for anybody.
My first 6 years at the company we were spoiled by having an accountant do our expenses for us. We just emailed her all our hotel and other CC receipts and she took care of the rest.