I'm not sure what exchanges your using... maybe it's that Yobit I keep hearing about?

Anyways, I'm pretty sure most exchanges don't do physical money... I mean, crypto-currency is digital.
If your considering USDT as a physical dollar... well, it's actually only $0.971, and it's a digital backed asset, so it's not.

I would assume, exchanges just don't want' to deal with the bullshit pegged cryptos that are traditionally broken