An EEA citizen who moves to the UK and is determined to be a "worker" is immediately eligible for in-work benefits like tax credits and housing benefit. However, their work must be considered "genuine and effective".[/i]"
They cannot. That is a very old article and is out of date. Even when it was written in 2015, they missed that the UK had changed the EU Regs for EEA citizens in the UK the previous year, in 2014.
The UK said they will no longer tolerate those who use Free Movement for what they will take and simply changed the rules, and will keep changing the rules. All this was said before the UK voted to leave the EU.
EEA citizen workers must be in work and cannot have UK low income benefits immediately when they find work. EEA citizen workers now have a 3 month wait for all UK benefits and must keep themselves or claim benefits from their own country. Some UK benefits now have a 2 year wait . They brought this wait in for British citizens arriving too.
It is that easy, the UK changes what they will give Brits arriving in the UK who have not contributed to the UK and that ends it for EEA citizens and their families too. That's why I said before that it doesn't matter what PM May agrees to as any future UK government cannot be held to that. The EU acknowledged that in the Withdrawal Agreement (if there is one) that the EU is bound to that but the UK will not be because of the way UK laws work.
For those arriving as EEA citizen jobseekers.
The UK changed to, EEA citizen Jobseekers arriving cannot have benefits and the UK decided they can only be an EEA citizen jobseeker for 6 months. No UK benefits anymore for these for the first 3 months now and then only £71 a week jobseekers for the second 3 months IF they can prove they are looking for work for 35 hours a week AND prove they are likely to get that job. No benefits anymore for housing, or for their children (Tax Credits, Child Benefit). After that second 3 months, the jobseekers benefits payment stops too.
Then the UK applied that retrospectively and those EEA citizens who had been "jobseekers" for years in the UK. These lost all their UK benefits, including benefits for housing and benefits for their children, benefits as they were ill. These could no longer pay their rent and several months later when their landlord was able to get a court to evict them, when they applied to UK councils for emergency housing as they were destitute, they were told that if they were destitute in the UK then they should return to their own EEA country.
https://www.freemovement.org.uk/existing-eea-migrants-at-risk-of-destitution-following-the-removal-of-housing-benefit/For EEA citizen workers, now if they lose their job they can only have 6 months as a jobseeker before all their other low income UK benefits end too (Housing Benefit, Working Tax Credits, Child Tax Credits, Child Benefit, Sick benefits like ESA etc), unless they retain workers rights, but that is time limited too.
Another popular move with EEA citizens,, is to move to a country where they think they will be given more in retirement. The UK has started closing that down too to make sure other EEA countries will give more than the UK.
The UK was taken to the European Court but the UK had ensured they changed within the EU laws and the UK won.
You only have to read the Welfare Reform laws that started as Bill in Parliament years ago, to see how things will change again for EEA citizens.
That's why I have been saying Brexit won't matter a jot to those using Free Movement for what they can take because the UK can (and does) keep changing the laws to make the UK less attractive to these: then apply those changes retrospectively.