but technically your prepared to owe the government upto 30% of it in tax if its paid into your account? While loans aren't taxable, it can only be classed as a loan if it has documentation detailing a reypayment plan and interest rate, Not saying you"ll pay it, just that technically its owed, and cant have tax credited off from your home country.
the two things you mention, tm47 & tm30 have nothing to do with visa's, they are stand alone requirements(laws), there are probably another 1000 laws you wouldn't be told about when you apply for a visa or enter the country.
Having a work permit is only one of the routes, being married is another route, the commonality is same visa extension of stay for 3 years and tax return receipts.
before brexit, you could travel to any EU country without a passport, and europeans can still travel within EU without passport. ASEAN is akin to EU in some repects.