Why no. It’s called escape and evasion.
You are not obliged to carry ID in the UK and there are immigrant communities from all over the world.
However, getting into the country can be problematic, a lot of effort goes into securing the border and you really have to walk and talk like a tourist on a short visit with plenty of money to avoid some close questioning by immigration.
This applies to people from anywhere outside of the 28 states of the EU and that includes US and Australian nationals who are well known for overstaying their visas (I daresay the same applies in reverse.)
Immigration is such a big issue in the UK that politicians are always pointing the finger at each other about failing to control it. So, there are regular raids by the border agency on houses suspected of being home to illegal immigrants and ethic restaurants. Having Robo-Cop bashing down your door at 7am is very frightening and there is a huge backlog of deportation cases. The Home Office department responsible for this is not well regarded.
However, these actions are intelligence led. It is not the job of ordinary police to deal with this, so people do not get questioned in street unless there is some special action, where they are accompanying the border force. Not having identification on you is not a crime, as it is in other countries. If you give some consistent answers, you are OK.
Interestingly, they have just started checking peoples passports on the way out of the country. It used to be a case of only checking those on the way in, some people would overstay their visa. Whether they have computer system that checks one against the other, I very much doubt. You can get into the UK from the EU with a National Identity card of any of the 28 countries, many of these are not high tech documents.
The UK gets 32million visits a year and as well as tourists, it the destination country for a lot of people fleeing persecution and poverty in their own country. For some reason they seem to think they will fare better in the UK if you keep your head down. On the other hand, the UK does not do amnesties for illegals, as they do in the US and other parts of Europe.
So what is going to happen if they don’t blend in?
“You know that guy seems out of place, I better put in a call to the authorities!”
That would be so bizarre in even the most backwards rural areas of the US, as long as our hypothetical guy keeps quiet and doesn’t make trouble no one is going to care.
The Canada/US frontier is the longest unguarded border in the world IIRC.
Just walk/hike across at any ole place and start fitting in…
.
Don’t know about credit cards, but, yes, you can open a bank account without a SSN.