‘if they wanted to they would’ is absolutely valid in some contexts. however, some people really, really want to and simply don’t have the capacity to do so.
Potentially unpopular opinion: if you can’t teach the whole curriculum without homework, your curriculum is the problem. Kids aren’t“quiet quitting” by expecting to only do work @ school. After 7-8 hrs of work, they should expect to protect their peace & find joy when they leave