> Why can't people just build products and ask for money upfront?

Asking for money is such an huge entry barrier. Even if it would only cost one cent, it would still stop 99.99% of the users from using it. I was kinda hoping for Bitcoin to fix this. But now it already cost a lot to make a transaction, and you can't instantly verify the payment. Paper money was a huge step, electronic payment was another huge step, lets take the next step!