That's true, however most receivers havea trimmer and coil to tune the receiver and antenna together for the best impedance match. It's not unusual for these settings to be off a ways. The radio in my truck was a bit weak until I adjusted the antenna tuning across the AM band.The radio stations in large metropolitan areasbroadcast with upward of 75k to 100k watts of power. Some media have repeater towers so that they can reach a larger audience.
I'm luck if the most powerful station nearest to me puts out 25k to 50k watts of power.