I'd guess the main reason is low tax on salaries, and less competition from finance than e.g. London.
I think google came to Zurich because of EPFL/ETH, the very high living standard and most of all the rather liberal labor law. It's very easy to fire someone in Switzerland, compared to the surrounding countries.
healthier economical setup I must say. also, if they decide to trash banks with some end-of-data-privacy law (and it will eventually come, as for US persons), it won't be such a disaster for their economy.
VAT is small (8% or 2.5% on essentials), but prices/fees are very high to begin with.