Not quite. The cable company does not have to put a channel on a particular channel. If ABC is channel 3 that doesn’t mean it MUST be cable 3.
The thing is since originally VHF was all we had on TV and that was channels 2-13 (forget ch1 that is another thread)
Bigger Markets tend NOT to have a channel 3 as the larger markets received the most VHF stations. For example in order to give NYC, LA, CHGO the most VHF stations they gave them 2,4,5,7,9, 11 (13 in NY & LA). That allowed for Max of 7 VHF stations.
You see you can’t put two VHF channels in the same city next to each other, except channels 4 and 5 or 6 and 7. Though they appear to be next to each other they are far apart on the spectrum.
The most you can get out of a channel 3 market is 3, 5,7,9,11,13 or 6 channels. The problem is you can use channels 2 and get 2,4,5,7,9,11,13 or 7 channels or 2,4,6,7,9,11,13 or still 7 channels.
So basically at first all the larger cities were given the 2,4…combos. Later it became necessary for other reasons to assign stations so it got a bit more complex. (For example they took Channel 4 from Chicago and gave it to Milwaukee as Milwaukee’s TV3 was interfering with Kalamazoo’s TV3.
So anyway people got used to the VHF dial and it became better to have a VHF number 2-13. Even better channels 2-6 are better (they are stronger) than 7-13. You will note in the late 70s early 80s many networks (esp ABC) changed high end VHF for low end VHF.
Now with TVs no longer using dials most of the original reasonings were outmoded.
With some networks they want the “VHF” channels (2-13) in a cable company (though for cable it don’t matter). For example FOX32 wants Channel 12 as 32 is similar to 32. I guess they have a 2 in them.
UPN50 in Chgo wanted channel 8 in cable as it is between Number 1 ABC7 and cable giant WGNTV9 (though in CHGO WGN is an over the air station)
So networks often bargain with cable companies for channel positions as it is easier for them to advertise.
UPN50 can say “Watch us tonight on Power50, Cable 8.”
Channel 3 is the most used for auxillary TV devices as Channel 3 is less used. You will not most devices let you use Channel 4 if Channel 3 is being used.
The must carry rule simply means that if a station broadcasts over the air they can force the Cable company to carry them. This helps small stations like (in Chgo) WJYS TV 62 or the PAX network.
Before this our cable company didn’t carry UPN or any of the small Chicago stations…TV60,TV62,TV66,TV44(the latter are Spanish Language Stations.)