That's true. As parents we must introduce all kinds of stuff to our kids so they can learn and discover what they like. The toughest thing is to judge what is "a solid effort". For example, when my parents told me as a kid that I had to try a musical instrument, I hated it for the first few months. But after a year I started liking it, gained proficiency and still play music today in my 50s. When my Dad introduced me to mechanics, I took to it like a fish to water from day 1. Two very different experiences but they both "stuck" just with widely different notions of "a solid effort". If they considered 6 months as a "solid effort" for music I would have quit and missed out on a life enriching experience.... Embrace your child for what they enjoy, if cars aren't it, let it go. Maybe it's baseball, maybe it's not. Maybe it's Barbie's, maybe it's not.
We encourage our kids to try something, if they don't like it after a solid effort, it's over. Don't know until you try, but you're creating a bad relationship if you try to force it.