Employees in Europe have to have fixed amount of hours in predictable schedule. There's no way it could be the same. It definitely would outclass many workers who would like to earn side income.
Given how much they earn it's very likely they're under the taxation threshold/within the standard tax break (eg. in Czechia if your total income tax is less than 1000 EUR you're not going to pay anything).
Healthcare is completely separate from your employment in EU. It's your personal thing to sort out your health insurance, you just notify your employer when you make a change of insurer (because the employer is sending them your money).
In some states there's a national insurance plan, in some you have a tax-funded healthcare, and in some you have mandatory health insurance (with private insurers, based on your income, 15-30%).