A whole load of banking products aren't legal in the UK, or are highly regulated; particularly sludge products which are easy to sign up for but hard to cancel.

UK banks are required to make their communications easy to understand and relevant. There are also regulations requiring banks to tell users when products may be unsuitable.

All UK companies have to adhere to the UK GDPR, which allows users to restrict what marketing can reach them.

So yes - a bunch of regulations.