Poor Bing
The thing about Google's dominance in search, and hence search ads, is that it's ephemeral. Google has no lock-in. The day there is something better, more reliable, faster, more current, we will all shift to it and drop Google like a hot rock. Google knows this, and spends immense resources continually making their services better.
This has been going on for some time, and Google's pool of knowledge in the field is vast. Their services are amazing. They have invested remarkable sums in building and got good value on nearly every buy. They've invested in great boffins too, and got good creative work out of them - work they give us after they've done it one better.
Others like Bing and Yahoo face this high hurdle to competitive share: they have to be as good as Google to gain viability in the long run. They cannot assume dominance and then shut down all opposition and progress and then halt their own improvement efforts in preference to rent seeking. I'm sure to them this looks like unfair monopolistic behaviour - that Google is preventing their dream by engaging in continuous improvement; by being so good Bing and Yahoo cannot compete or even buy the market.
That is hard for Bing and Yahoo. But I'm OK with it. It is not unfairly anticompetitive to be unapproachably the best at what you do. It is not fair to ask Google to hop on one foot so as to give the slow kids a sporting chance in the race.