> pet projects answer a thousand questions that a cv and an interview cannot.
If the answer is 'no' you'd have to ask a lot of follow up questions, some of those may be illegal, to decide whether or not having pet projects is even a possibility for the applicant.
> What type of work does this person enjoy, are they building libraries for developers or products for end users, A lot of time people will open source their side projects, you get insight into their working practices, how clean their code is, do they test, do they get caught up in details and not the end product.
Yes, that may be true. But having pet projects is not a pre-requisite for employment anywhere.
If you can not assert the ability of your applicants during an interview by asking them job related questions then maybe you should let someone else do the hiring?
> Sometimes people pets projects are working on a large open source project, for employers I believe that is the jackpot, you have their communication with users and peers, the output of their work and the thought processes that go along with it.
That is absolutely the wrong reason to go for this particular applicant because that is simply none of your business. You get what you pay for, the time they spend on the jobsite and the output they generate during that time. You have zero title to 'their communications with users and peers' and so on, and if you lay any claim to those then you're a very bad company to work for (yes, I know there are companies that do just that).
> Employing people is not about giving every developer in the world an equal opportunity for a job, its about finding the best people for your team in a minimum amount of effort
Surprise. Employing people is all about fairness and treating your applicants - and your employers - with dignity. What they do or do not do during their time off is none of your business.
The reason I would not want to work for a company like that is because I would doubt the long term viability of a company that sticks their nose in places where it does not belong.
Typically this is indicative of a 'we hire people like us' mentality. You will likely find that places like that employ just stereotypical copies of the person that runs the place instead of being representative of the workforce in general.