They may also have safer jobs with less exposure to carcinogens. Heavy industry jobs are often located beyond a reasonable cycle commute from people's homes.
Less than a hundred years ago you would have factories in city centres and people commuting there from within a walking distance.
Nowadays both environmental regulations and land prices pushed all that to the outskirts.
The last 30km along the expressway leading to my home city are lined with factories, logistics centres and whatnot and I'm sure most workers there commute by car.