It is not performing exactly as Bitcoin. There's clearly more on-chain competition for Bitcoin block space, and that's why it comes more expensive.
When usage and on-chain competition is concerned, you are right nothing come close to bitcoin but the code, the way mempool works, the way fee spikes take place, etc. are very similar to bitcoin. We even saw this same behavior in shitcopies like bcash that have a much bigger block cap
https://bitcointalk.org/index.php?topic=1776143.msg52337255#msg52337255Being expensive (dollar wise) in general depends on both the price and competition not just one.
Otherwise even setting the fee rate to the smallest possible value for bitcoin and all its copies (ie. 1 sat/vb), the bitcoin transactions are still more expensive because bitcoin price is higher.