exactly. the reason for asking for a receipt is forensics.
but most of them are printed on thermal paper these days and those fade fast even when inside a relatively sealed container (UV eventually burns the blackened thermo sensitive layer that has been blackened).
so if the only option was thermal paper anyway, the email will last longer.
it's notable that for the most part if the reason for the receipt is tax they print one out on fancy letterhead format with mostly whitespace, and usually on a laser printer, and it has some prescribed tax receipt format and possibly your tax registration number under your name.
for the most part these days everything is digital anyway.
digital signatures are becoming a thing a bit in some places and mostly optional but eventually keys like our nostr keys will be the norm in business.
for right now, the whole thing is wide open for easy, evidence free tampering.
