I can't tell at this point whether you are trolling, or one of the HN hivemind that actually believes sending cash in an envelope is somehow faster and more secure than using a blockchain and cryptography for payments.
Personally if I want to send money quickly and securely, be it within the UK or internationally, I use the banking system. It's cheaper, its faster, its more secure and if someone makes a mistake it is easily reversible. I even send a monthly remittance to Madagascar for free, and its not exactly known for its advanced banking system what with it being the 4th poorest country in the world. Yes it takes 2 to 4 days to get there, but I can pay anyone within the EU instantly or if its an American there's always paypal.
I'm 90% sure at this point that the main reason that cryptocurrencies became so popular (apart from the opportunities for massive fraud and bilking of the gullible) is because the USA has a banking system that has barely evolved since the 1980s. I mean they were still flying cheques around in 2004 and I still have American businesses trying to pay me by cheque on a regular basis in 2022. When you consider it through that lens it's no wonder Bitcoin sounds like a good idea.
Sending money with a UK bank or PayPal is the opposite of privacy preserving. The convenience of it is fine for UK to UK and EU banks, not great for private, secure, instant and international payments.