In most cases carders wont change the billing address to their drop address, because its hard... So at checkout when carding physical items, wouldnt it be an automatic decline if the shipping and billing address are different? How do people not get declines because of this?

Some shops don't use AVS, same with countries. Usually USA and UK use AVS but there could be a shop that doesn't use that so you can bypass AVS.

stores are diffrent.

you have to look for a merchant that doesn't use AVS there are few around but not one will give those t you.
few I know is PS4/Xbox Games
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Some sites offer an option to ship to a different address as a "gift" - although this does not always solve the problem, sometimes it may work. If you have the full info for the associated card, you can try an Enroll and/or COB on the card.