These questions always seem to arrive as a pair.
The requirement to pay income tax (if we focus on just one tax) is a combination of Income Tax Act 2007, section 4 and (for this year) Finance Act 2022, section 1.
HMRC are given their collection and management powers under Taxes Management Act 1970, section 1.
Links to the legislation are here:
You may think so. Even if you are taxed less than the equivalent incomes in many other countries.
Here is an excellent blog by Dan Neidle on this topic: https://www.taxpolicy.org.uk/2022/10/10/employee-tax-comparison/