Despite the differences, it acts roughly like a coinjoin, but it is actually much better. That said, another proof that the supply is not verifiable is that we cannot perform sidechains such as Liquid with Monero's characteristics, nor drivechains (if we could) with Monero's characteristics, because we could not guarantee that 1 BTC = 1 BTC in the sidechain or drivechain; the relationship could be broken at any time.

The supply is verifiable. Monero nodes verify the supply all day and night long.

a coinjoin is a cooperative transaction. Monero doesn't need to do that.

Not exactly technically but maybe "default coinjoin" is a useful analogy when explaining it to someone newer... though unlike coinjoins, amounts are hidden and address reuse on-chain is made impossible.