Not all stainless steel is magnetic, it depends on the nickel content of the stainless steel. Non-magnetic stainless steel has a higher nickel content. And yes, there is both magnetic and non-magnetic stainless steel cookware available. Non-magnetic can't be used on induction cooktops and as I mentioned earlier, also has a higher nickel content. I've read that nickel can accumulate in the kidneys and cause kidney damage but can't find my reference on that right now so this would be something to investigate if people were concerned about a higher level of nickel exposure in their stainless pans.
Also, if you want to ensure you have magnetic stainless steel, you want to make sure test the inside of your cookware as that is where your food touches. Because, yes it's possible to have one type of stainless steel on the exterior and a different type on the interior. So, a person may decide they are fine with their cookware that is non-magnetic stainless on the exterior but magnetic stainless on the interior, unless of course they use induction where non-magnetic won't work.