They can't wear a helmet over the turban? If it's too small, they could wear a larger helmet. Is it against their religion to not have the cloth on their head? Like couldn't the helmet act as the head covering? Couldn't they wear a type of helmet that covers more of the head, like a motorcycle helmet?
There are a bunch of helmet options for Sikhs now, and the original purpose of the turban was for battle...it can be wrapped around a hard shell helmet without a problem. I have worked with pretty devout Sikh men who wear ball caps over a cloth hair cover. It saves a lot of hassle, and they put their hard hats on after swapping out the cap. I've never been on a site where someone refused a hard hat, but I'm not in construction... I know compliance is a lot harder on that industry. Half the roofers can't be bothered to tie off in my province, so we pay for their idiocy quite often. Plus, we are cramming nomex cold weather balaclavas and hoods under there in winter...once you get used to that, the turban thing is a really dumb argument. You can definitely get one to fit under a hardhat. Likewise a hijab. For six months of the year EVERYONE wears a Nomex hijab FFS.
Many services (police, etc.) have a modified uniform. You can't wear a purple turban with your police uniform, you wear the police one. I think this is a good example of inclusion, tbh.
The knife thing has been tested and retested in Canadian Court, most workplaces accept a dull knife as fine if they have very strict rules on weapons. Mind you, it is totally acceptable in Canada to carry a folding knife or even wear a hunting knife in many places, so it's not like this is "special" outside the city.
In terms of forbidding Halal, I get that. The slaughter techniques are controversial, and for good reason. They could be sanctioned under animal cruelty if not for the exemption. Same with Kosher. The butchering requirements for both are very involved, and seem largely to serve the purpose of employing religious officials. For many smaller abbatoirs the cost of providing Halal and Kosher can't be offset by a cost increase...but it is significantly more costly to perform. Factory operations I'm not sure, but small producers are not taking in huge profits as it is. Unless they have a ready market, a large population essentially demanding kosher or Halal, it's not feasible.