Google pay little to no corporation tax on profits in the UK (because they ship all of the profits overseas where Corporation tax isn't so expensive).
But Google employ lots of people in the UK so they do contribute a non-insignificant amount to the UK treasury in the way of taxes related to employees (PAYE/CGT on share option grants, NI, etc).
They do the former because they can, the do the latter because they must.
Google pay little to no corporation tax on profits in the UK (because they ship all of the profits overseas where Corporation tax isn't so expensive).
But Google employ lots of people in the UK so they do contribute a non-insignificant amount to the UK treasury in the way of taxes related to employees (PAYE/CGT on share option grants, NI, etc).
They do the former because they can, the do the latter because they must.