I don't think that is correct especially for mortgages. The whole point of an ERC is to make up for loss in interest over the duration of the agreement.
Alternatively you can invest that money elsewhere to offset interest.
For example my mortgage it's 5% for an ERC reducing by 1% every year until it's 0% at which point I can change deals or pay without any ERC.
Also on mortgages with nationwide you can overpay by 10% of the original mortgage amount without any charges. So you can make overpayments to reduce interest by quite a bit penalty free.
It would make zero sense to pay 1-5% to end it early as I could be making 1-5% on that money instead. It's entirely dependent on the arrangement in place. But you would be better off cancelling out the interest by investing than paying an ERC and losing money.
If you'd won say the lottery, then swallowing the ERC isn't a big deal. The interest you'd earn on the would be payment would be a pittance these days anyway.
Also if someones house had increased in value and they needed to move, but mortgage wasn't portable. The increased value of your property would then cover the ERC.
I imagine most people don't bother due to its cost. My ERC on the first year of my mortgage was over 15k.