This photo was reversed 180 degrees for comparison with other photos. This is a mechanically efficient position, although aerodynamically poor. Some riders may have difficulty achieving a low forward body, aerodynamic posture because their pelvis has to be rotated forward. It is a more complex matter than simply lowering the handlebars. The rider would initially be slower in a more aerodynamic, lower position. Once there was adequate adaptation on the part of the cyclist, a lower, more aerodynamic posture and position could be achieved.
Note that extended training on an indoor trainer tends to reinforce bad aerodynamic positional habits. What works on an indoor trainer does not necessarily work out on the road. In fact, the more efficient a position is mechanically, the less aerodynamic it tends to become. The secret is achieving both.