It’s more likely to be down to incompetence. I can’t imagine the party UV lights are more expensive than the fuck-you-up UV lights.
EDIT: Someone else mentioned these might’ve been used during COVID for sanitation, and are extremely cheap leftover wares now that the pandemic is “over”, which would actually make them a lot cheaper.
I would strongly assume Protonmail will be doing this automatically soon, there’s no manual day-to-day verification necessary.
Writing to the Blockchain is difficult and takes processing power, reading from it is absolutely trivial though.