There’s also fees that the administration can levy as payment for specific acts, they’re bound to that act.
Social security payments are not taxes.
In the same way, donations are not tax (but because they are just contributions to the welfare, they are tax-deductible).
Compulsory Social Security payments to the Government are as much tax as VAT.
There are lots of mandatory payments that are not taxes: To register a car, you need proof of insurance. Mandatory, government controlled, not a tax. Want to build in flood plains? Some regions enforce a flood insurance. Mandatory, not a tax. Want to register a business in germany? Need to be member of the IHK and pay membership fees. Mandatory, government enforced, not a tax.
Money paid to the Rentenversicherung, to health insurance etc does not go to the government. It goes to semi-private entities (mostly Körperschaften öffentlichen Rechts) and the government has very little control over it other than negotiating the rate and negotiating the mandatory payouts. The money does not go to the government, it cannot be spent on anything other than the purpose it way paid for: Arbeitslosenversicherung pays for the year of Arbeitslosengeld, pension funds for your pension and health insurance when you're ill. All of this may be additionally supported by taxes, but that money comes from the regular tax pool. The individual health insurance providers are actually competing and you, as a member can vote for the governing council of your health insurance.
I agree with you. In my experience most people in Canada, and perhaps the US too, consider any government mandated deductions from your gross salary to be "taxes," regardless of the final destination of the money.
This is why you have people arguing that health care contributions and social security payments are "taxes"
Source: lived in North America and Europe