(I can't explain why CNN Money or Trulia would change it though).
Most likely the same CYA reasons they would have also implemented the Cookie Disclosure in recent years. Even if US-based and expecting primarily US-only traffic, major company doesn't want to be legally liable for any issues arises with EU compliance, just from curious visitors. (Not to mention the obvious gray areas of EU citizens residing in the US.)
The more hopeful answer is that possibly because of GDPR and indirectly recent Facebook/Cambridge Analytica, at least some companies may be doing it simply because it is a good idea, whether or not they think GDPR applies to them.
What I did read made me think that I really need to look into replacing my webmail provider by something else, like ProtonMail. Unfortunately, changing would require getting a lot of family members (who are less tech savvy than I am) to switch my email address from one they've been sending email to for decades.
I don't think the original problem is like "if you don't like our privacy policies then don't use our service" versus "you guys are screwing us selling our data" type of problems. Let's make a fair trade. Again, I don't mind sharing some of my data if you guys can generate money to support your service. Just tell me exactly what it is so I can make a fair choice.