I bet you my other employeer would tell you otherwise. 220 is the main “interoperable” spectrum block but not the only spectrum used.
My cohorts over at BNSF are using 220 and VHF locally.
And the agreed (not lawfully enacted) standard originally authored by the AAR in cooperation with the railroads, FRA, and FCC would prove them wrong.
As to BNSF, I've done installs in the Los Angeles, Chicago, and Powder River Divisions. BNSF is setting up all their PTC for 220 with Sinclair vertical dipoles. Other than voice, their standard plan upon completion will only leave VHF active for HLCP, and ARES (Burlington Northern's early version of ATCS). Hell, Dave Freeman, BNSF VP of Engineering, had a hand in the creation of the 220 PTC standard.
The standard is what the standard is. No Class I or Class II has deviated from it yet, and they would stand to take regulatory major penalties from the STB and/or FRA if they did for hindering interchange. Which is why the AAR 220 Standard was created in the first place.
I gotta say, honestly, It's frustrating that there's so much misinformation on this site when it comes to rail communications. Including route name errors and various operating details in many of the railroad frequency databases.