This is right.
It’s partly because one way or another they have to give you a CME data-feed (via “Rithmic” or whatever) which actually costs them something.
So it’s not the same kind of business as a forex broker giving you a permanent demo account, because that data feed is only a feed of their own prices, which doesn’t cost them anything.
That said, you can get some big discounts, up to 80% or even 90% on occasions. The trick to that is just to get on their mailing lists and await special offers.
There’s a bit of information here -