Because the women aren't allowed to be involved.
I wrote a feature this month for Swiss News on women's rights concerning the Sechselaeuten festival. For over 21 years now, a group of women have been asking for equal rights to participate in the Sechselaeuten Parade and have not been able to obtain it. 21 years. That's how slow things are to change in Switzerland. To read more about the battle between tradition and modernity in both public and private Swiss life, click here to read, Sechs-ism, Beyond the Böögg.