Probably because the bulk of the products tested were likely kids toothpastes.

Lead Safe Mama community members nominate products for laboratory testing and then the LSM community uses crowd-funding (including through GoFundMe) to raise the funds to cover the costs related to testing and reporting of these nominated products. This is how the toothpaste and tooth powder products listed in the chart below were chosen for testing, and how the testing and reporting was paid for.