Look at the trough in the cloud behind the C17
That's the best picture to see the effect on airflow from the passage of the aircraft: the cloud is lowest along the keel, not in two tracks behind the wingtips.
See the 757 wake smoke too - ten lengths back, you have a dipole-field-like flow.
Alongside the posted picture you reference: there is almost no compression of the air. Dynamic pressure, certainly, but no bulk compression.