Ballgunner, you are right that sweep is used to delay the onset of compressibility effects in jets. However, vortex generators are seen on both straight and swept wings, they add energy to the boundary layer and delay flow separation. They generally are placed to correct or minimize some quirk discovered during flight test. Although some fighter aircraft are basically unstable without computer aid, all transport category aircraft must meet inherent stability requirements for certification.

Sweep does indeed affect low Reynolds number, and subsonic aircraft. Moderate sweepback behaves similarly to dihedral and is used in most pattern airplanes for that purpose.