I think consumers have to take some responsibility for the choices that they make - always assuming they have enough money to make a choice. I have never shopped at Primark, but I understand the pressures of trying to clothe a growing family on a very limited budget. Having said that, it is very difficult to source so called ethical clothing, and we have to take quite a lot on trust. I think one of the problems is that we have become used to cheap clothing, and lots of it. A bit of sunshine and the shops are packed with people hunting for summer clothes, although realistically we will be lucky to have enough decent weather to wear them for more than a few weeks.
Last year, I read Factory Girls by L T Chang, which puts Chinese factories under the microscope. From this, I learned that it takes 9 or 10 hours to produce a pair of Nike trainers, typically selling in the UK for £70 or £80. You don't have to be a maths genius (which I most certainly am not) to work out that by the time the raw materials, advertising, shipping etc are paid for, there's not going to be a lot left to pay the workers.
The argument that countries like Bangladesh need the trade was also used to attempt to prevent the introduction of fair trade coffee and bananas, yet both these products have gone on to commercial success.
I agree with previous posters that we could reintroduce clothing manufacturing in the UK if, and it's a big if, consumers were prepared to pay the true cost.