I honestly do believe a better bait will out fish a rubbish bait, but as @kevtaylor pointed out the water itself will make a difference. Fish a rich water where bait may not need to be eaten and you want a decent bait. Fish an overstocked water (and to be honest, most are) any bait may catch.
Humans can choose what they eat by thinking, they can choose to eat healthily or not. Carp don't have that choice, Survival, then health. They have to eat what is available, natural food, or pellets or boilies, or maybe particles, even more so in a high stocked environment.
I have seen good baits 'dominate' a water, the right bait outproducing every other bait used to the extent of that bait being almost the only one that caught, and it was not particularly heavily baited, around 1kg a week, after an initial 20kg in 2 weeks.
Yet Mainline baits have also dominated waters, the Essex Grange, the original Grange CSL, not a bad bait, Activ8, not bad. The Cell, not so good.
There is a difference in quality between the bait companies. Some 'Joe Bloggs' garage specials can be produced for exactly the same as the Bait Baron bait, Nash, Mainline etc, but you forget Nash, Mainline are sold nationwide. The cost of that bait may well be £4.50 per kilo, Joe can sell it for that. Mainline or Nash might well sell it for that price as well, but the middleman, (wholesaler) puts his bit on it, so it then gets sold at £7.50 per kilo. Tackle shop buys it, final selling price is £10.99 per kilo. NOT every tackle shop buys direct from Mainline or Nash etc. In the interests of retail the RRP of all shops is £10.99. So Mainline might have different price bands depending on who they sell to, or selling to a shop directly at £4.50, the shop may be able to sell at a big discount. Is the bait market fair?
Most definitely not!
I can tell you for 100% fact that Crafty Catcher boilies are sold in the Gladwell's shop, right next to the Crafty Catcher factory, Gladwell's own Crafty Catcher, for exactly the same price retail as most tackle shops that sell them.
I bet most bait companies with retail outlets adjacent as part of the company are the same.
There is an element of price fixing!
Baits can be discounted for various reasons:
Get rid of, it is not a good seller.
End of line
Make way for the new stock, either new product or newer model.
Discount to increase interest, loss leader
Or even nearing end of life, even frozen goods have a life.