If you think about the kind of controls you'd have in place for a laundry; choice of detergent, temperature of wash, glass policy, segregation, etc. etc. It would be laughable and I could not be controlled as well as you'd like.
Ok though, let's be pragmatic. Lots of standards / certification bodies still permit this so how could you control it practically? First of all, risk assess. If you make RTE chilled food or work in a high risk / high care facility then I'd suggest you shouldn't be doing it but low care / packaging, perhaps you could argue the risks are low, particularly if your foodstuff is not suitable for pathogen growth. You need to record this risk assessment.
Then you need to validate as far as you can. I would suggest you give guidance to people on how to wash the smocks. You can't complain at people doing it wrong if you don't tell them! Then I would suggest as a validation exercise you do extensive swabbing of smocks to prove home laundry is not presenting a risk.
Then verification, you'd have to do ongoing visual and swabbing checks of the smocks to ensure they're not presenting a risk and as verification that people are laundering them!
But long term, your customers are bound to eventually demand that you launder them in a laundry designed for the purpose. So it's probably best to cost up what the costs will be for the validation and swabbing / auditing and suggest to your boss you move across. Note you can often hire clothing which then takes out the cost of repair and replacement and spreads out the cost.