As said above, TR's are an optional item. First, the braking system on the EMB-145 are fantastic. The weight savings without the TR's is around 700lbs, which that far aft makes a difference. For the most part all of the non-T/R equipped aircraft were delivered new to European airlines, but a few have made there way on the secondary market to the US.
"It's not the size of the dog in the fight, but the size of the fight in the dog"