They raised the transaction to 1usdt per withdrawal over a month ago, probably because trc20 usdt was getting more deposits and withdrawals than their BUSD, so they decided to make some money off usdt withdrawals, and it's no longer just Binance last week I tried withdrawing TRC-20 USDT from kucoin and I was charged $1 too, seems like very soon time every exchange will want that too.
Binance want more and more money, as usual. And they want to push you to use BUSD
Everyone wants money, that's just the main aim of doing business satifybthe customers then make money off them, that's just business for you.
After all having low withdrawal fees, it is their way of calling the attention of people to use it which is normal in a business. What happened today is just normal when talking about business it nvolves making money. I guess the main reason having high fees is that many uses it. The higher the demand is, the higher fees it have, that is business.