Right now there are not enough test kits to evenly distribute, or just to create an accurate sample size to gather data. The tests we are using right now are ones that we send into a lab to retrieve the results, and it is on 70% accurate leaving a large gap for error. But there are other options being pushed forward one is a rapid test kits, these allow you to see if you carry the covid virus or not.
Another big reason that these rapid test are important and might prove very effective in the coming future, is because they are a lot more inexpensive the the traditional test and they are 90% accurate. Traditional test cost hundreds and the rapid only cost 20-50$, at the moment they are not used as much because insurance and healthcare does not pay for the rapid ones but do cover the conventional test.
Being able to get results right then and there will help people be more cautious, but will also help get a data sample and see what prevents the corona or what makes you more susceptible. We also will be able to see the rate of spread and where this spread is continuing from.