In Estonia, the employer's expenses are 1.75x of what the employee actually receives; 43% of the employer's payroll expenses go to taxes and other fees. I assume it's similar in other EU countries.

You can buy health insurance separately, but that doesn't excuse you from paying taxes if you're receiving income. And once you're paying taxes, there's no point to buy health insurance separately, as you will automatically qualify for "free" healthcare. The only time it makes sense to buy health insurance separately is if you have retired at a young age or you're cheating on your taxes.

Of course, all of this varies by country, but I imagine the percentages are relatively similar. Germany is a more expensive country, so I can see how 70EUR/h might be a reasonable number there.