Incidentally, I never understood why Thatcher was evil for not subsidizing the loss-making mines, and modern politicians are evil for subsidizing loss-making banks (i.e. RBS).
Some view Thatcher destroyed the industry not only because it was unprofitable but also as an attack against the unions, supposedly going so far as to shutdown even profitable mines or those that had potential. Putting 180,000+ out of work is going to cause some outrage from those you are putting out of work & the surrounding communities that relied on those wages. Also some may view domestic energy production as a valuable asset to retain even if it is not market viable just due to energy security/independence concerns.
As far as the bank comparison, I think some people have a kinder view towards the plight of a coal miner working in dangerous conditions for not a lot of pay vs the plight of an executive banker raking in massive bonuses while tanking the economy.