One of the decisions that LATCH is supposed to remove from the equation is "Where in the car should the seat be installed?" In previous vehicle (and seat) generations, figuring out the best mounting points were often a problem. It's difficult to navigate the maze of seatbelts in the backseat of most cars (which belt half pairs to where?) and a combination of shoulder harnesses and slack, manually-tightened lap belts made for messy and uncertain installation.
So, LATCH came along and, again, promised to make it easier.
Each LATCH-ready car is supposed to feature at least two sets of lower anchors and corresponding tethers. For the purposes of symmetry (one could reason), in cars with the minimum two sets of anchors (which is to say, most cars, with the exception of some SUVs and vans), the anchors are found on opposite sides of the backseat. In other words, the anchors implore the car seats to be installed next to the windows and doors.
But, critics howled, tradition and common sense dictate that the safest place for a child is in the middle of the backseat, away from the doors that might fly open in a crash, and away from the windows that will probably shatter! This goes against everything we've been told for years!
Well, replied automakers and seat designers and government safety experts, if you really want to, you can use the leftmost anchor on the passenger side, and the rightmost anchor on the driver side, as a set of center anchors so the seat can be installed in the middle. But, it won't be safe in every situation. The required anchors can't be much farther apart than the anchors normally are -- in other words, there can't be huge gaps between the seat base and the anchors that would allow slack for the seat to slide around. (Experts recommend no more than 1 inch (2.54 centimeters) of space between the anchor hardware and the seat mounting point.) The fit and installation must be as snug as it would if the seat was installed in the "official" location, and the tethers must hold the seat firmly in place, with no leeway to tip forward.
So, if you have a LATCH-equipped car, you'll have two obviously-designated mounting points, and if your old notions of safety standards overrule the new standards, then you have a little flexibility, even if the whole point is to avoid flexibility. At least it's easier to install the seats when they're right next to the doors. And besides, if there was one middle seat and one side seat, parents would essentially have to choose a favorite child each time the family took a car trip, putting one child at less risk than another.