Tax rates for everyone, start at 0% and mostly rise so those with the lowest income are at an advantage.
Paying into a pension is a popular tax efficient "move". It starts with zero income and as it grows it hits a max so again, it's not such a benefit for wealthier people.
Societies in countries thoughout the West have a bunch of reasons for tweaking the personal and corporate rates, not least to maximise the take or encourage societal advantage.
If you're going to earn 50kpa from dividends, you have to lend the company a couple of £mil by buying shares which may drop. Divis from even say Exxon now are only ~3%, so you're not keeping up with inflation. Obvs you could do better or worse. You pay tax on the income at almost your marginal rate. Forget ISAs, too small to cover it despite what bitter and twisted others here have said.
It's fair because the rules are the same for everyone. Some individuals like to find or invent inconsistencies they don't like - very possibly without much knowledge of relevant reasons, which very few have. Certainly not me.
The whole set doesn't suit me/us particularly well, we hit the descending pension pot limits a few years ago.
(There's a new Pan European Pension Product. Looks complex.)