I could see someone arguing you need a specially trained staff member or supervisor to verify your ID for anti-scalping, which they don't need to do for other e-tickets. Say only one person uses this option all season, they could be asked to pay for an entire employee's salary/benefits.
It's a bit hyperbolic, but supporting non-standard workflows is organizationally expensive with many non-quantifable costs.
And there is precedent on the pricing. For example, FAA is not allowed to charge any more for any service than it costs to deliver said service, which is why if i lose my pilot's license, a replacement is $3.