This is just one of the examples of many shortfalls of today's Internet. The entire premise of the Next Generation Open Internet Directory project is based on taking the Internet beyond these shortfalls and into the next generation. Data is trapped and owned within applications. A classic example is MS Word. On the Internet, service providers own data, that users enter.
Most job sites provide services by captivating user supplied data.
Competition is based on how many job seekers and employers are listed in the database verses the level of service these sites provide. All auction transactions that are carried out on Ebay are Ebay's property or so they claim. This keeps users away from taking advantage of the offerings at other Auction sites without spending extra effort. Or it may have some information about you that you may not want to reveal. You have no control over the information that these sites carry about yourself.