I think it might be because microsoft charges money for windows licenses and you can't keep it free of charge and pay for licenses for the lab vms. But for exp

I think it might be because microsoft charges money for windows licenses and you can't keep it free of charge and pay for licenses for the lab vms. But for exploit labs,you just need to give learners the samples and/or something like an ansible playbook to setup the vm and they can run it on their own box.