pilots and doctors are doing OK, and have unions.
They may have unions but only because an individual pilot or doctor cannot afford to buy and operate their own airplane or hospital.
Freelance writers have no need to have a union or any other kind of a 'professional organization' because all they need is a free email account to start working on their own.
if I did some work for a USA company and was classed as a full time employee, surely that would make my tax more complex rather than as a self employed individual in England?
Not only more complex. In fact, the company would have to withold about 30% of your pay as taxes of foreign employee. Living in the UK, you would never see this money or get any "benefits" (not too many benefits either way).
It seems the official goals of 'editor75' are to:
1. Organize freelance writers and make them fully dependent on their employers.
2. Make all freelance writers as poor as a church mouse (employers would pay them a minimum wage, if anything, having no ability to control them).
3. Make writers do projects they have no interest/ability/desire to work on and on schedules of their employers, not their own.
4. Kill all the benefits of working online from any country you like.