It could/should tho be changed so that health insurance up to x% of income is tax-deductible, but only if freely chosen on a free market by the employee, with a

It could/should tho be changed so that health insurance up to x% of income is tax-deductible, but only if freely chosen on a free market by the employee, with any other constellations being taxed as regular income, without the tax-deductibility. There can still be plans only offered to employees of a specific company, but the issue of preventing an employee from shopping insurance himself is gone.