I would just say, I do blame ISP’s for trying. It’s unethical to try and squeeze every cent out of your customers, community and country. It’s never just “business”. Businesses are operated by people while exploiting people. It’s not a cold hearted machine doing the thinking, it’s normal people making these unethical decisions.
If we’re just looking at the grinding of the metal wheels against the rails, it’s very little. Some metallic particles are produced in the normal wear but ferrous metals easily react and oxidize into more inert and normal forms for life.