Because I noticed in my trezor wallet, when I tried to use it with mycelium wallet, you can select any address type you want, either legacy address/P2SH address or bech32 address.
In Electrum you have to creatae a new wallet (even if you use the same seed) to change the derivation path (which is what the addresses type are, a different derivation path)
However, in coinomi for example, you can use all 3 addresses type in the se wallet. You can use in funds from 2 of them in the same transaction and receive the change in another, for example.
So, it depends on which wallet you are using with your trezor device.