Engineers are not really commodities. The right engineer can really push your business forward and become a powerful asset. The wrong one can set you back years while your competitors surpass you. As long as there’s companies out there who want the best, the best will command higher salaries.
If you manage to hire a great engineer for a cheap price, inevitably they will have no loyalty and leave your company for a higher offer. Thus losing you money in the long term and harming your business. A remote worker can do this easily.
If you want cheap, the unethical thing to do is hire local talent that doesn’t enjoy remote work and can’t move easily. You entrap them into the job and pay them less.