My assumption is that those Sanitary tees on their sides are the vents for each sink. Per code, a vent cannot go horizontal before it reaches 6" above the flood rim of the fixture being served. And while there is a debate about using a Sanitary tee on its back for a vent connection to a drain line, it definitely cannot be used on its side for a vent. Nor can it be used for a horizontal change in direction for a flowing drain if those tees happen to be from another fixture on the other side of the wall and there is a vent is inside the wall.