How to make developers love security
helpnetsecurity.com
helpnetsecurity.com
That's a heck of a long answer for "it's not the immediate objective of their work"
It's like asking "Why some receptionists find security burdensome"
--> If no one defined the framework and tools for them to let people enter/exit in compliance with a buildings' access-requirements, you can't blame them for "not doing it properly"...
Because some are paying attention! :)