Why does the coverage of two operators from one BS not match?

Question

mobile connection

For example, Yota uses the power of Megafon. It is logical to assume that where Megafon catches, Yota should also catch.
We open a coverage map on their sites and see the discrepancies in the signal boundaries. We go to the area, we see that the Megaphone actually catches 4G, only 3G is indicated on the map. We look at Yota, 4G does not catch, where Megafon was caught, Yota did not even catch 3G.

Answer 1

Because Iota can not be allowed on the entire frequency range, but only where there is capacity. At lower frequencies, it may not be easy, but they are more "long-range"