Because a lot of people never consider Bing Search Engine Optimization (SEO), thhey do not know what is takes to rank well on Bing.
Bing SEO is different from Google SEO. Most people think if they optimize for Google the same will apply to Bing. This is simply not true
Some Key Differences between Bing SEO vs Google SEO
Bing favors old, reputable pages whereas Google prefers fresh, regularly updated content.
Google is more likely to rank your internal pages such as blogs and services, whereas Bing is more likely to rank your home page.
30% of traffic on Bing is ripe for the taking.
With a little background research you could get your Real Estate website ranked on the top of Bing's Search Engine result pages.
You'll be in a a smaller pond but it will be much easier to get the fish biting.
Ranking well in Bing can also effect your Google search engine rankings too.
Think about it.
If you get to the top of Bing search results this leads to 30% more exposure.
This, in turn, means that you end up getting more back-links and discussed in more related forums and more comments sections.
The same goes for your Bing PPC ads.
You can use Bing PPC ads as your "way in" to boost your rankings on Google search engine results pages.
This can help increase your local brand exposure without directly challenging the biggest players in your niche market.