If you want to sell digital goods or if you need a notification on your shop that client made payment you have to use a third party or a node or a smart contract
Use a proper wallet.
Not one crypto solved the problem of allowing merchants to sell their own digital goods easy
There's cryptocurrency plugins for pretty much all relevant online shop solutions.
To deploy a smart contract costs money each time you need to update it and you have to create a dapp for it
Why would you need a smart contract for offering centralized services?
To host a node costs money ( hosting fees )
Use a SPV wallet.
To use a third party costs money ( fees )
Don't use a third party.
What's the point of a crypto if i can't use it as a merchant easy and without extra fees ? I could just use paypal or credit card processing ...
That sounds like you've never used PayPal or credit card payments for business.
We must solve this problem
What problem.
The merchant should easy copy/paste a code and put it in his html .
There you go:
<a href="bitcoin:33jr6swgJxHwyFTgXKcv7kbKSy4du8Yt8r?amount=1">Pay here</a>