The part 15 rules for intentional radiation on the AM band are reasonable if this "permission" is intended to allow an individual to transmit to his own radios at home.
The combination of "100mW to the RF final" and "3-meter vertical antenna" produces just the right signal strength for use within one's home and adjacent property.
My kitchen radio is located 7-feet from my AMT5000 Wintenna installation (the metal window frame is part of the antenna), and the radio overloads from being "too close."
To reach the kitchen radio with less signal strength a second transmitter/antenna (different frequency) is located 35-feet away.
If the FCC allowed more AM signal strength all the radios in the house would over-load and it would be necessary to locate the transmitters outdoors somewhere as far away as possible, limited by the size of the yard.
It is probably true that the FCC never intended AM part 15 to reach a distant audience, although it is not expressly forbidden, for which reason much effort goes into doing just that.
Placing the transmitter in outdoor space with ground radials achieves amazing reach.