Another angle to that is that telcos and banks are localized services (none have high % market share across the globe) that people use less frequently than email. Whilst they carry potentially higher rewards for blackhats, in an aggregate effect on society, a single bank not being secure is probably less noteworthy than a globally used service like Gmail or Facebook not being secure.

Also, banks only deal with money, whereas in certain locations and situations, lives potentially depend on Gmail, Facebook and Twitter being secure. (oppressive governments and such)