An anti vortex (A/V) cover is safer than the old style covers, but they are all safer than no cover at all! Typically, when there is/has been an entrapment, it is because there was no cover installed and the drain was wide open. Any time that the pump is running, and suction is present, there is the possibility of entrapment, even though very slight.
The VGBA law and compliant covers are something that have value of course, but never should have been an issue if people paid more attention to their pools! A missing cover is not only unsafe, it is irresponsible! The fact that a Senators granddaughter had to die pushed the legislation, or else we would probably never have changed drain covers much.
I get pretty wound up on this stuff. I've been building pools for almost 15 years now, and I was taught from the beginning to use split main drains. This is even more important in the "one pump chump" pools where an oversized circulation pump is installed for the sole purpose of being able to supply jets in a spa when in spa mode. There is, in my opinion, absolutely no reason to cheap out with one pump to save a couple of bucks (if you can afford to build a pool you can afford one more pump!) when building. It costs more money in the long run in electricity, and creates higher suction rates, increasing entrapment opportunities.
OK, I am getting off my soap box now; rant over! Be a responsible pool owner, replace your cover(s) and enjoy your pool!