The massive irony of this bit, of course, is that, while you don't need permission to open a block, merely proof of useless work, you do need the permission of the particular miner to have your transaction placed on that block.
Here's a short guide to transaction fees. Basically bung a bit on and hope for the best. It is then out of your hands.
And the very decentralised nature of the thing is its limiting factor - only 1 mb of information per block, so per 10 minutes. That's a very small and strict limit on its potential use value.
Explaining bitcoin transaction fees
Priority fee means it will be confirmed in an hour. That's the more expensive, 'fast' option. Meanwhile, when I buy things using Visa, it's confirmed in, what, three seconds?
Aside from the traceability issues for illegal activity, I still fail to see why anyone would choose to use something like bitcoin to make transactions.