Making your customers happy is the only route they have. When governments or other third parties get involved then you and I might no longer be the customer, but I can assure you that the corporation is still serving their customers.
That's the number one problem with our current situation in the US with healthcare. You are not your doctor's customer. You are like, 3 layers away from being his or her customer.
Just look at how Wells Fargo a while back was opening up accounts and charging fees to customers who never authorized it.
Or Purdue Pharma that gave kickbacks to doctors to prescribe opioids and misled the public about how addictive they were.
Or payday loan companies that suck people into vicious cycles of debt. Or the numerous companies that profit from gambling addiction.
Or the big banks that gave out dubious mortgages and lied about risks to investors, which precipitated in a global housing meltdown and recession in 2007.
Or how cigarette companies lied about the dangers of smoking, leading to countless deaths.
Companies will lie, cheat, and scam their way to profits if they have to. Not all of them, and not all of the time, but the endless quest for more money is always corrupting.
Also, you have to understand that public corporations get cash from people buying their products and services and from investors. The investors are therefore just as much their customers as you and I are. Often it feels like investors preferences are given far more deference than your and my preferences. In a free market, we can pay attention to that and make choices accordingly.
Finally, your opioid example is very pertinent to the original topic. You and I were not Purdue Pharmas customers in that scenario. The doctors and insurance companies were. We are just a weird cost of doing business caught in the middle.
The free market works when there is actual competition. If we want a healthy free market, then we need vigorous antitrust action to block mergers and break up companies that get too big.
I also would recommend that government should stop making regulations and tax breaks that favor one company over another. I think that would be even more effective than just antitrust enforcement.