Not necessarily. Here in California at least you can transfer into a 4-year college after you've done 50+ units at a junior college - no test scores required.
The colleges are much more interested in how you did in those classes and whether you could succeed in that environment than what any test score was.
In fact, I've been told that colleges prefer the older transfer students to the newbie 'tested' freshman because they former has a higher rate of 'serious' students and more often than not perform better.
Here in MO, the community colleges either give you the option of submitting ACT scores, or taking their own placement tests. They admit pretty much everyone, but they don't have to put the student in classes that they don't think the student can handle.
But just an observation: I find it interesting that people who wouldn't touch a public high school seem to have no compunction about sending a 16-18 year old to a public community college, where the instructors have *far* less "brakes" on them than they do in a local high school.