"Mike Coslo" wrote

And that 50 watts affects calss A different than Class B?

Of course not. (This is another of those 'novel' questions.)

But my intention is that the Class B (learners permit with training wheels)
test be ultra simple, to allow as many applicants as possible. For that
reason, requiring qualification in esoterica like "Biological Effects and
Exposure Criteria for Radiofrequency Electromagnetic Fields" is
inappropriate. Thus the 50W power level recommended by the NCRP and
ANSI/IEEE ensures a modicum of safety for these beginners.

In the process of preparing for Class A (without training wheels) license,
the candidate would need to explore the RF-exposure safety issues which
would be on the qualification test. Then we could expect that they'd have
some appreciation of the hazards and how to ensure that their station is
engineered in compliance with the MPE criteria mandated by 97.13(c).

73, de Hans, K0HB