Why are the fees hard coded?

Question

Most cryptocurrencies let you choose your fee. Why does Monero use a hard coded fee?

Edit: Or rather I should say why is the minimum fee hard coded.

Answer 1

The fees are not exactly hard-coded, the amount per kB is hardcoded. This was enacted after the block overflow attack where the attacker had to expand the blocksize by flooding it with transactions until they were able to fit more than 512 transactions in a single block, which they were able to do for little cost because tx fees were so cheap at that time. So, the switch to a fixed fee per kB was done to make any kind of flooding or spam attack much more expensive to pull off. I believe the intent is that it is a temporary measure, and it will be removed allowing for dynamic tx fees per kB in the future.

Answer 2

I doubt most other currencies do not have hardcoded fees.

In any case, some research has started a while back into making fees a function of the past. Variables that could have an influence on fee include block sizes, and transaction volume. Monero price is an external metric, so that seems difficult to integrate into a dynamic calculation, and, if it were to be included, would likely need maintainer input to change it.

A spam attack in 2014 caused the fee to be increased as a first defense. This fee is expected to decrease should the price of monero increase substantially against fiat currency.