The higher you set the fee's once you have sent a transaction there is the chance that you will be first in line, meaning sending transaction will be faster, try to set your fee's at low and it will take hours or a day, that is the reason why they set fees at a higher one.
Did you not read what I said? There is no reason to set the fees at 50 sat/vbyte if you see that the mempool has less than 1 MB of <1 sat/vbyte and 0.5 MB of everything else. Then you can set a fee of 2-5 sat/vbyte and it will get confirmed in the next block with a high degree of probability. Setting fee at 50-60 or 80-90 sat/vbyte in that kind of scenario has no purpose other than flushing money down the toilet. Similarly when people set the fee at 600 or 1000 or 4000 as I have seen.
I'm adding this as visual for akirasendo17. There is no need to set a 50 sats/vbyte when mempool is less than 1 mb. Maybe you can set 2 to 5 sats/vbyte in anticipation of more incoming transactions but to say setting a higher fee without looking at the size of the mempool first is wrong.

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Is it simply because of how default fees are set in wallets, by exchanges, or by services? If so, why do professional developers miscalculate the fee so poorly?
I doubt they miscalculate. I believe that's intentional. They want their users to have the best experience as possible and that includes instant processing of transactions.
As you know, many of the new bitcoiners are still noobs when it comes to these technical topics and are probably lazy to even read. If these exchanges and custodial wallets sets fees lower than the current highest or optimal fee, the chances are they will be bashed by their users for being slow.