Why tax parents of third-level students?

IT seems the powers-that-be will do whatever they can to reintroduce fees for third-level colleges. All this in a country where one can vote and get married at 18 and drive a car at 17. Of course children’s allowance ceases also at 18.

Yet it’s proposed to tax the parents of third-level students, most of whom are 18 by the end of their first year, for their education. A 20-year-old car owner’s parents, for example, are not forced to pay for their offspring’s motor tax. Why should they be forced to fund college fees?

Why in every other way is an 18-year-old deemed to be completely independent except when it comes to third-level education?