> ... what assurances do you have they would not comply ...
While compliance is certainly not optional, the value of your compliance is highly dependent on your technology. (The authors mention this in the article by writing that Apple does not collect the same kind of data as Google.)
I think it is like choosing VPN providers. You never know if they were involved in compromising their customers until they are caught compromising their customers.
So if you have a choice between two similar VPN providers, and one of them is known to be involved in compromising their customers, you use the other one.
I do not see how this would be any different with search.
I quit using DDG because when it ran out of answers based on what I searched for, it would spam results of 'random word in search query + city/area based on IP address'. Which was not only completely useless, but creepy as fuck.