I suspect you're a decade or two out of date to say that people in the UK go contracting to avoid taxes (there's a world of legal difference between 'evading' and 'avoiding' taxes, starting with the fact that the latter is legal and the former isn't). Those of us who choose to work as contractors also usually avoid job security, company pensions, redundancy payments, and many other benefits. Some of us contract because we like to move around, or because we prefer the customer/supplier relationship to the employer/peonemployee relationship, or for any of a number of other reasons. There are some contractors who might as well be permanent employees, contracted in the same place year after year, but a) they're usually subject to IR35 these days, and b) that's usually because their employer imposed those conditions on them to avoid future redundancy liability.

As to 'incapable of getting a proper job' in theory it's possible to conceal a lack of competence by skipping from contract to contract. In practice, interview processes usually (OK, not always, but usually) stop that from happening.

Update: But all that's way OT. I do agree that there is no sense in having a 'Perl Contracting' section on the site - it's way too specific.