The fee will increase as the price of bitcoin increase or if bitcoin is bullish.
I am constantly doing deposits and withdrawals and every time I send from my wallet, I should set the fee to .70 usd or more to confirm faster.
When I withdraw, I also noticed that trading sites paid over $1 for transaction fee and they don't charge me anything on that, they have a free fee for every withdrawal.
That is absolutely untrue, there have been coincidences but no, the fee has always stayed more or less the same in satoshi, but you feel the pinch because of Bitcoin's ever increasing price. In fact, that's also not accurate. Ever since new upgrades, Segwit being the most obvious, fees have been decreasing in terms of satoshi. More transactions inside a block and smaller transactions so of course fees are cheaper.
What kind of wallet lets you set fees in USD? That's a very strange wallet.
This was a topic from last price hack and the current situation is a bit different from last one. At the time of creation of this post, transaction price for Bitcoin was above $5 for most wallets but today the transaction fees are much lesser and hence Bitcoin is still a viable currency for gambling.
But if you want to save more, there are much more alts option than were a few years ago.