Exchange wallets, hardware wallets and web wallets: Why don't they all have a seed recovery phrase?

Question

Here's what I think is going on

• Exchange wallets for ether have no seed recovery phrase. Only one's log-in and password to their account on the exchange grants access to their wallet.
• Hardware wallets for ether have no seed recovery phrase, but the hardware device itself does. Meaning that losing the device, and recovering crypto on a new identical hardware device using their device seed phrase grants access to their wallet many times over.
• Web wallets like MetaMask do have a seed recovery phrase.

What explains the difference in the fact that, all the above are by nature Ether wallets, no more no less, yet only web wallets require the owner to set up a recovery seed phrase for the wallet itself?

Is the owner more or less in control of their private keys for one of the options in the list than the others?

Answer 1

Exchange wallets...

(Centralised) exchange wallets may or may not be wallets. They could simply be a database or spreadsheet acting as a ledger to record the balances of the users. When you deposit funds onto a CEX, you pay either into a communal wallet along with everyone else, or into a throwaway wallet that the exchange controls. You don't get a seed recovery phrase because you are never in control of the "wallet" - in whatever form it takes - anyway.

Hardware wallets...

If a hardware wallet supports multiple currencies, then it's likely they all use the same BIP-39/BIP-44 seed phrase standard. As such, the same device-wide phrase can be used to seed accounts for each of the supported currencies, ergo only a single seed phrase is needed for the device.

Meaning that losing the device, and recovering crypto on a new identical hardware device...

As long as the device has used a known seed phrase standard (e.g. BIP-39 - they all do as far as I'm aware) then the same seed will work on any other wallet. You wouldn't need to buy another identical device.

Is the owner more or less in control of their private keys for one of the options in the list than the others?

"Not your keys, not your coins."™ (i.e. For the case of centralised exchanges.)