They ask you to cooperate. If you don't want to, you don't want to. In my experience, most travellers cooperate.
In the Portuguese PLF, you can enter any fantasy data you want.
In the Spanish PLF, you are merely required to indicate the town and the autonomous region were you spend your first night but you must indicate a correct email and a correct phone number otherwise you will not receive the QR code that you must have when you want to board a plane to Spain.
France asks you to fill in a form "on your honour". If you don't have any honour you fill in what you want.
No country is wasting human and financial resources on checking much if anything of what you entered on your PLF form.
And, it's been two years of this so it gets a bit

but, yes, I know, you were just trying to be funny.