No, they shouldn't. That would be utterly ridiculous. Perhaps companies should also be allowed to set their clocks however they like too? Before you call out strawman, explain to me the difference. Standards are standards for a reason. If you haven't thought about what that reason is, or don't understand it, you have no business sharing your ridiculous opinion about it unless your intention is to come across as an idiot.
I am very au fait with both imperial and metric measurements as I used to work in a brewery. Having to switch between the two, not only in terms of production, but also plant was and is a complete pain in the **** and a waste of everyone's time and money.
It should be totally illegal to sell anything that requires quantification measured in anything but standard, metric gradients. By all means display an equivalent, or use different nomenclature, but the standard is the standard. 568ml of beer please barman. Call it whatever you like. And top it up please.