Cynthia. Trulia is merely a website that aggregates listings. They are not in charge of the listings, nor do they make the decision as to whether, or not, to respond to inquiries. If listings are not calling you back, that's an issue with the Realtor...not with Trulia.
Trulia won't know if there is an application (or 60) in on the property. It's up to the Realtors/Landlords to update and remove the listing.
You're right. It's ridiculous.