That is mostly true, PLA is ONLY biodegradable in a facility that can handle that. Your run of the mill recycling center in your city probably can't or won't take your PLA prints.

And then only if it's pure PLA with no additives. Which most PLA has to improve speed of printing or strength or some other property. In practice, I'd wager that 90% of commercially available PLA fillament is not actually biodegradable.