This all came about because of boiler explosions at the Gettysburg RR and at a steam tractor meet in Ohio back in the 1990s.
The federal government stepped in, taking over steam rules and regs from individual states, and tightened the rules on what they call "antique and hobby boilers".
They also cracked down on full-sized steam power. See how many steam operations are not running steam anymore? How steam restorations are becoming more complicated? How most railroad shops cannot legally restore their own boilers anymore? Because of two accidents, the feds stepped in.
Privately held steam power, even "small" ones like this, are subject to all the tightened rules and regs. The states have to enforce the federal rules.
Yes, it stinks. Thank the lax rules (PA and OH) that allowed these accidents to happen in the first place.