For example, in the USA, "You generally must withhold federal income tax from your employees' wages. You withhold part of Social Security and Medicare taxes from your employees' wages and you pay a matching amount yourself." - http://www.irs.gov/businesses/small/article/0,,id=172179,00....
"If you classify an employee as an independent contractor and you have no reasonable basis for doing so, you may be held liable for employment taxes for that worker" - http://www.irs.gov/businesses/small/article/0,,id=99921,00.h...
I assume that the US law allows "contracts" that are "signed" or agreed with one click on the "I agree with the terms and conditions" checkbox, and this contract would establish the paid individual as an independent contractor, and then the paying business has no burden of tax payment on behalf of the individual.
Do you have any information about the legal framework for similar issues in UK or Ireland?