Heat pads ("UTH") work well to provide comfortable "belly heat" for good digestion in snakes. It mimics the sun-warmed rocks they seek out in nature. BUT, you're correct that if they're too hot (over 90*) a snake can get "burned" by laying over them too long without realizing their mistake, & BPs (perhaps because they're heavy-bodied & it takes longer for the warmth to "register"?) seem prone to making this mistake. It's up to us, their caregivers, to prevent it.
The main reasons snakes may get "burned" from UTH heat is either they're not regulated properly (controlled by a thermostat & properly monitored) OR, there's too much substrate over the UTH, allowing heat to build up, & then the snake digs down into the substrate, pushing it away, & ends up laying on the over-heated floor of their enclosure. The substrate over UTH should not be very deep, to help prevent this from happening.
There are options for heating a snake's home- overhead options work too, but ALL must be regulated for safety. What each person chooses can depend on what they're comfortable using & what kind of snake or what kind of enclosure they're using. There are ways to make each option work best, which is why we share our tips here.