I don't know much about how BTC or ETH works, but why all cryptocurrencies takes so long to confirm a transaction. I think even 30s is too long, why cant it be instant like PayPal?
Just learn more about how paypal transaction works, it is not instant because transaction can be reversed even after 180 days if buyer file a chargeback claims. On the other hand bitcoin and eth transactions are non-reversible so when they will get few confirmation there is no way to reverse it.
Cryptocurrencies are way better than paypal like centralized payment gateway which can froze your millions of $ with very weak reason anytime.