Just because something directly harms the competition doesn't mean it's unethical or immoral. If it doesn't harm the stakeholders, it's fine with me. This isn't pouring waste into a river. This is going in and poaching the opponent's resources.

I also don't think it's inherently dishonest to do things like offer referral bonuses for getting the competition's drivers to join your service.

Were I an investor, where would I get the impression that they would shamelessly cheat me at the first opportunity? All they've done is improve the likelihood that the business I have invested in wins out.