TL;DR: For USA registrations, if you create a NEW AppleID, there are ways to complete the registration process without entering a credit card. If you have an EXISTING AppleID, you always need a credit card to complete the sign in process.
CAVEAT: I don't know what happens if you create a NEW AppleID, select None, and someday you have to re-accept the TOS and/or re-enter the payment screen. Will your "None" option still be available at this point?
As stated in many other threads, I think the biggest confusion here is between NEW Apple IDs and EXISTING Apple IDs. I ran into this problem when I opened iTunes, tried to sign in with my existing ID, and it made me re-accept the TOS and prompted me for credit card info. Wouldn't let me Continue without putting in credit card info.
My USA based EXISTING Apple ID does not have the None option. Unfortunately, I think it's as simple as that:
If you want to setup a NEW Apple ID without a credit card, there's a bunch of hoops you can jump through that are detailed in many other posts - these involve downloading a Free App and things of that nature.
Sometimes, you need to re-accept the TOS (for instance, loading up iTunes and it tells you that you haven't used this device with iTunes before). If you sign in with an EXISTING Apple ID, you will not be presented with the None option. You have to put in a credit card.