I disagree that they compete on trust. A CA is either trusted on not, they have to stick to the rules to stay in the browsers lists - but as see all the time -

I disagree that they compete on trust. A CA is either trusted on not, they have to stick to the rules to stay in the browsers lists - but as see all the time - do the bare minimum to keep in the game. But as a user of certificates, there is no levels of trust to compare, either the padlock is green or its not. So I look only at price, and maybe more abstract things like customer service.