Keep in mind that in many places that have sales tax, the company can claim reimbursement for that tax if it was expenses for the company. Sometimes the rules can get arcane - no refund for consumables like paper and ink used in the offices, but refund for fixing a machine that produces the items you sell, etc. To claim a refund, the company must if audited be able to show the tax refund claimed was from an actual tax collected by an actual tax-paying company in that state, with registration number. (In Canada, for example, need company GST number…) While an accountant might let some things go (Hmmm… those were the days - Feynman spent $2.36 to park at the airport for a day or more?) there’s a limit to what they can let go.
I know I’ve never had a hassle with claiming taxi expenses including tip, but if it was to the airport ($30 or more) then I DID get a receipt - “$33 for the trip - put $40 on the receipt and I’ll give you $40.” I never lied, but I wasn’t cheap with the company’s money - it had a reputation to uphold… For minor things, not so much. We also had a per-diem, you could claim the $50/day (a long time ago!) or provide receipts. Since I never drank, per diem actually made me money.
One time a fellow I worked with and I went to a computer show out of town. We could either take the prop puddle-jumper to the nearest big airport and fly from there, or drive to the airport. The mileage allowance was more that the prop plane fare, so “…to the maximum of equivalent air fare”. We drove in my car, I claimed the equivalent air fare, then the other guy’s boss insisted on him taking equivalent too. (I suspect that this was a dodge that others had used to make money, and his boss didn’t want to raise alerts for future claims). Years later they changed the rules and you had to provide the gas receipts to prove you drove.
Yeah, Feynman was being a dick, as was the accountant. Of course, an expense for $2 back then is like an expense for $20 or more today, so not trivial. OTOH, it’s probably a lot cheaper to fly today than back then. They should have a procedure, tolerate missing receipts if it’s less than $X and the total for the whole reimbursement is less than $Y. But anyone who thinks the government, or any large corporation, is going to reimburse an airline ticket without any documentation is delusional, especially in those days when one local flight cost more than some transatlantic flights cost today. After all - yes he was at the meeting - but he could have driven, he could have stayed at a friend’s instead of a hotel, he could have been dropped off at the airport instead of parking there, etc.
The purpose of reimbursement is to replace out-of-pocket expenses, not to give you a tidy sum which you can pocket if you can cut costs yourself.