The cost of externalities are covered when litigants claim damages.
Litigation has never been, and will never be, an adequate substitute for judicious regulation. Many harms are very real, and serious, and well recognized as both, without being litigable. To suggest otherwise is tantamount to saying externalities should just be ignored in the name of profit.
That's a complete fantasy, litigation is expensive, it should be reserved to exceptional cases not to dictate basic rules for society...
Sometimes damage claims are just the cost of doing business.