Higher cost tires don't come for free. You either pay for them by ordering an option, swapping them before taking delivery, replacing them after purchase, or if the manufacturer selects a higher cost tire.
The common factor is that you pay for the tires, just as you pay for everything else in the trailer.
Some people have noticed that the pricing on an upgrade to Goodyear G614, which includes profit for the tire manufacturer, the tire distributor, Heartland, and your RV dealer, may be more than you would pay to upgrade them yourself after purchase, considering that you can usually trade or sell the original tires. That may be due to taking RV dealer profit out of the mix.
Heartland has been moving away from Towmax, but obviously the transition is still underway.