In this situation,bitcoin cannot fix its transaction caps and high fees,because its decentralized digital currency and
beyond uncontrollable due to different circumstances.bitcoin is volatile in the blockchain market and every platform site's has a different transaction caps or gas fees of there services.
This is about the tx fees not about fees a platform or a merchant is asking for.
And secondary, bitcoin is not that uncontrollable as you think.
Did the code decided for itself to implement segwit? No , it was implemented by developers and accepted by the users, so it can be modified again and again and again as long as users and miners go along with the new version.
unless you can think of a way to increase the block size to 1 TB and reduce the time between blocks to 10 seconds while solving the orphaned blocks issue, there is no other way to increase the transaction cap. there will always be a cap no matter what you do and increase it has its own issues.
A block of 1tb and 10 seconds delay , would mean an increase of over 60 million times in capacity that is way over what would be required.
But even 100mb blocks would probably make most of home users unable to host a full node.
I keep an eye on the blocks BCH mines and I've stumled uon numerous transactions 1M in size with 35k inputes or outputs. Pure spam that will lay on your hdd forever. Oh, and the fees where 0
How to change the amount to lower? This is a decentralized system and a free market. You want speed , you pay for that more than the one that doesn't.
Double spending has no effect in this.