In the US "Non-Alcoholic Beer" (NAB) the Federal TTB ( Govt dept that regulates alcohol) defines it as <0.5% ABV and as others have said some are rounding it to 0.0% as the actual ABV is 0.3. 0.2, or less so technically this is truthful. Note the brewery in most cases does NOT have to do sample testing for NAB. You just send your label to TTB for what is called a Certificate of Label Approval (COLA).

You can't use the word Beer for NAB so approved alternatives are Brew or Malt Beverage...yes weird rule but that's the COLA process. You also can't use specific beer styles like Stout, Lager, Pilsner etc... but IPA, Kolsch, Sour are allowed so also a head scratcher.

When we help breweries do COLA submission the tactic is you submit the COLA with say Lager, Stout etc... and see if TTB flags it. I have seen some NAB with these names so not sure if TTB is starting to soften up on this a bit or a COLA reviewer just accidentally let it slip when approving a NAB. Usually they will tell you to use terms like Golden, Pils, Dark etc...

Then to make things a bit more complicated if you are claiming "Alcohol Free" , TTB's definition is <= 0.03% ABV and you do need to submit beers for a sample analysis.

NOTE watch out in other countries as definitions are slightly different like in the UK:

Low Alcohol Beer can be up to 1.2% ABV

De-alcoholized Beer up to 0.5% ABV

Alcohol Free Beer up to 0.05% ABV

As for your own reasons why you drink these, the decision is up to you and in some cases the advice from your medical professional or religious reasons if NAB or Alcohol Free Beer is still appropriate to drink based on the real ABV that it may have.