If I pay with Visa, the seller is not able to see my account balance. With bitcoin, the balance of every wallet is publicly available.
Even without these privacy-focused wallets, you can use an HD wallet, where "child addresses" derived from a never-directly-used root key cannot be connected by a third party, unless you do something to connect them, by e.g. transacting with coins from both wallets from the same IP or in the same transaction.
The CoinJoin paper details the level of anonymity that it can offer. I could cite it to you here, but I am not convinced that you would read it if I did.
And in the PayPal use case, you wouldn't even see a single receiving address, as it's entirely opaque to that and it'd all be handled in some internal PayPal ledger. The receiver of the payment would only see a transfer to them denominated in local fiat currency. They might not even know the source of the funds was crypto at all.