I don't even understand thatm that's hurting their own production. Do they think you can work effectively after a fucking heatstroke? This is ridiculous.
It's got nothing to do with productivity. The worse the working conditions, the less mental and physical energy workers have to spend on organizing. Maintaining effective power and control over the serfs is the only thing more important to businesses than short term profits.
It's much less nefarious than that for most places.
Air conditioning (heating and cooling) is another expense they'd rather not have. Business will never offer to pay more than they have to, it's antithetical to their existence. It's what's happening at my job right now.
Not defending it at all, see my other comment in here explaining how I suffer from it too, just helping explain at least one reason why businesses choose to not care.