If that is the case, how many users even put a passphrase on it? Do they tell you in the instructions you must do this?
They don't go out of their way to highlight this issue... and, from a commercial standpoint, it's fairly understandable why... I mean, it's not exactly a great look to say "hey, our device for securing your coins has a fundamental flaw, but you can mitigate it by using this passphrase feature".
Most of their documentation seems to indicate that the passphrase functionality is "optional"... and not recommended for new users etc:
It is possible to add a passphrase to your Trezor, which allows you to make your Trezor impervious to any physical attack. Even if someone stole your device, disassambled it, and broke the chip to extract your recovery seed, your coins would still be safe.
...
Using this feature effectively and safely requires an understanding of its mechanics - if you are not sure how the passphrase works, we do not recommend using it.
Additionally, you have to go into the advanced options in the wallet interface and explicitly enable the passphrase protection functionality on the device. It is not turned on by default.
Granted, the more likely way to lose coins is probably carelessness with the seed phrase (ie. phishing sites or poor security practices and storing data digitally etc.) but still... they do seem to be deliberately ignoring the problem rather than addressing it in a meaningful way... which is a touch disappointing.