I haven't done a great deal of international travel or even gone to Canada often. I am aware of the fact that outside of the USA for the most part the rest of the world uses the metric system. Despite this, on TV even in international competition, especially in ones involving weights the measurements are done in lbs. I have ho idea why this is but it does seem to be the case. Maybe USA invented weight lifting or bodybuilding competitions or something.
src
I think that most gyms in the USA don't even bother with KG plates for the most part and that is a real shame because it would be a great learning experience for people. I guess most people don't actually go to the gym to learn anything though.
My gym unfortunately has a delightfully awful mix of plates that are kg or lbs, not both like the one above and it wouldn't really matter if they were doing both on some of the plates because that wouldn't really help matters.
Some of the plates are 5, 10, and 20kg plates and especially at the 20kg level this is where things because a grab bag of whether or not you are going to get a metric or standard plate. They look relatively similar while they are on the rack but when you pull down what you expect to be a 20kg plate only to have it be a 45lbs plate, this is really annoying for someone like me that lifts very specific weight stacks. 45 lbs is NOT 20kg. I realize that it is close, but it is not the same.
src
If you are the type of weight lifter that just goes in the gym and lifts "whatever" then this won't bother you a great deal but to be fair if that is the kind of lifter you are then there is a really good chance that you aren't using 20kg plates anyway.
I sometimes push my heavy limits by somethings as small as 1.25 or 2.5 kg. So having that extra kg or even a fraction of kg floating around in my stack is going to throw off my record keeping.
To make matters worse the barbells in the gym are all in kg but the machines are in lbs. This is just poor design on the part of the gym but to be fair to them I think they got all of this stuff 2nd hand, it certainly looks like that is the case.
I think it would be nice if particular gyms could just come to a consensus before they even open the doors or buy their equipment in one or the other form of measurement and never both. I know people that simply avoid the kg plates altogether because some of them are only even labeled in one measurement form and they don't even know how many pounds a kg is. I'd be willing to bet outside of the USA that the reverse is also true.