Why is trichomoniasis more prevalent in women?

More symptomatic: It is probably not more prevalent, just more symptomatic and easier to notice.

Doubt it is: Among women aged 14-19 years old the prevalence of trichomonas in the us was 3.1% but it was 13.3% in african american women. Prevalence in males has varied in different studies. Prevalences are higher in std clinics for both sexes. In men it is more commonly asymptomatic and detection is higher if semen is tested(rarely done). True prevalence is probably similar for men and women.