The Guru Take
Rideshare receipts? Taxi receipts?
In many localities, taxi drivers are required by law to produce receipts at the competion of the ride. In larger cities, taxis are required to produce printed receipts, but in most cases they can be hand-written receipts.
If you forgot to ask for a taxi receipt, try visiting TaxiFareFinder.com. They are not official receipts, but their results are often submitted to many authorities who accept them.
For rideshares, the receipts are generally emailed to you or simply displayed on the smartphone app.