Historically you might like to thank Gordon Brown.
IIRC correctly he thought it a corking wheeze to change the tax rules on employer contributions to final value pensions and bag the govt some serious extra cash.
AFAIK no later govt has seen fit to reverse his changes.
Naturally the pension offered to senior civil servants and MP's remains fully Gold plated.
Still who needs a company pension scheme these days? Pension schemes are about rewarding long term loyalty and staff spending their whole working lives in the same company. Since CEO's now seem to be playing a game of perpetual musical chairs I imagine they find it hard to see why anyone else should have their loyalty rewarded for decades of work.