I know what you mean, but I don’t think that Mastercard charge backs are generally better than section 75. They have advantages, sure (especially that for section 75 each individual item must have cost £100 - £30k), but also disadvantages.
For once, Mastercard charge backs only apply to the amount you paid by card. If you buy a car, and put only 1p on the credit card, and pay the rest by different means, the credit card provider is liable for the whole thing under section 75, not just the 1p.
Another point where section 75 wins is this: imagine buying a PC. A few months after purchase it breaks. Your merchant and producer have gone out of business, or are just a pain to deal with (may be based abroad, and don’t speak English too well, or not subject to English law). Under section 75 the credit card provider is now liable. Under mastercard charge back, you most likely lost.
So, when it comes to “buyer protection” yes, I think charge backs usually win. But section 75 goes much further.
Finally, I think that the fact that section 75 is enshrined in law is a big win as well: makes it much more difficult for a provider to try and wiggle out of it…
But, yes, charge backs certainly have advantages as well. Which is why paying by credit card is great: you usually have both charge back and section 75