One observation: it's totally feasible for a UK citizen with simple tax affairs (income only from employment, bank interest, shares) to file their tax return using a form supplied by HMRC (IRS equiv.). My understanding is that individuals in the USA have to use software made by Intuit and others, as the calculations are too complex to allow an average Joe to do it themselves.

Is this the case?

(I admit that 'ease of compliance' and 'tax code being complicated' are not the same)