If they were that bad the company wouldn't exist as we'd all buy genuine.
I disagree. You need to look at the markets, there are always going to be people out there who will buy at the bottom end of the market and it doesn't matter what market it is, an inexpensive alternative almost always will exist - sadly not for the Nivomats fitted to my car though! People will buy bottom of the market for financial and reasons of being realistic. Why buy a £200 Makita drill/driver to put up 2 shelves in a bedroom! You're going to consider that £19.99 deal in Aldi!
If for example I am buying tools I look to the likes of Bosch, Bacho, Makita, Husqvarna etc. but Rolson and Toolzone still exist. If I am buying car parts I will tend to either buy OEM or genuine, I buy genuine particularly if I cannot be bothered doing my research and working out who made the original part or doing cross referencing. Would I buy Britpart, yes for some things, the little cap that goes over the bolt on my seat-belt is Britpart, the bezel for my rear door lock is Britpart.
Last month I needed to drill a hole through some steel cladding at my business premises, I needed a long metal drill bit to go through the first sheet, through the insulation layer and through the second steel sheet, I had 8 holes to drill. I found the bit I needed from Screwfix for about £19 - I decided given this was probably the first time I needed a long metal drill bit and I only needed to drill 8 holes I would look to eBay - two 7mm x 200mm Toolzone drill bits for £2 or thereabouts inc. delivery. These drills must cost about 10p each to make, they are pretty badly made, the metal is odd and discoloured and they still have stamping marks on the flutes, they are not nice things, but they did the job.
So my point is that there is always someone, me in the case above willing to buy low quality stuff or people forced to buy low quality, some people are always trying to do things cheaply or in my case above wisely, £17 saved and job complete. From decorating homes to fixing cars low quality products will continue to sell.