There is choosing the right tool for the job, and then there is evaluating the tools against each other on the properties specific to the job.
If after making your tool selection you went on to author a study about how gas cars result in more frequent bathroom breaks while driving, without controlling for the length of the trip, you’d be doing what these folks did, and that’s selection bias.
If after making your tool selection you went on to author a study about how gas cars result in more frequent bathroom breaks while driving, without controlling for the length of the trip, you’d be doing what these folks did, and that’s selection bias.