The thing is you should have to be kept the fee at an average level. Otherwise people who are making smaller transactions are struggle with high transaction fees. It shouldn't be a regressive fee( like regressive tax, the tax rate decreases as the taxable income or wealth of individual or entities increases) but it should be progressive (progressive tax, the tax rate increases as the taxable income or wealth of individuals or entities increases). Progressive fee or taxes can be used as a tool for income redistribution providing social welfare programs, and reducing wealth concentration. They may promote greater social equity by shifting resources to support lower income individuals.
Transaction fees are not set by any one person or entity—they exist in a free market. The more people who use the Bitcoin network, and the more complex their transactions, the longer it takes for the average transaction to be processed, because there are only so many miners, and their processing power (and time) are limited. So as the number of Bitcoin users increases compared to the number of miners, the more you’ll typically need to pay to get your transaction processed in a timely manner. Of course since fees are paid in Bitcoin, the higher the Bitcoin price, the more your fee will be valued in USD, even if the same fee a few years back would have only “cost” a fraction of the current amount.
Transaction fees are high or low depending on how long it takes transactions to be included in a block at any given time. If there’s a higher backlog of transactions waiting to be included in a block, then transactions will take longer to be included in a block. Transaction creators can include a transaction fee, or set their transaction fee higher, to increase the incentive for a miner to include their transaction in the block candidate.