Not all, only "cyklista mladší 15-ti let musí používat ochrannou přílbu" (the cyclist younger than 15 years must use a protective helmet). Some members of parliament reasoned that old women going to fields would look ridiculous.
I have never seen such a dangerous motorcycle environment. OK, I take that back, it was even worse in Afrique and Bénin. The Czech Republic is not as dangerous as either Afrique or Bénin.