Not necessarily, much harder to prove a direct link to age. It's plausible that Developer B had more experience due to either not going to university and worki

Not necessarily, much harder to prove a direct link to age. It's plausible that Developer B had more experience due to either not going to university and working as a ruby dev , or perhaps doing freelance ruby work whilst at university. It's also plausible that Developer A worked for a corporation as a Java/Python/Whatever dev for X years and would not qualify despite being older. So it doesn't necessarily discriminate based on a person's age, any more than requiring a university degree will generally discriminate against people under 21. In the driving license example, you must be 17 or older to hold a driving license in the UK. Therefor by requiring 10 years of holding one you are literally barring any person under 27 from the job.