Can gliders and single-engine planes have vortices? I read,

A third physical explanation of the source of induced drag is that the
wing tip vortices contain a certain amount of rotational kinetic energy. This
energy has to come from somewhere; indeed, it is supplied by the aircraft
propulsion system, where extra power has to be added to overcome the
extra increment in drag due to induced drag.

[Source: Introduction to Flight by John D Anderson, Sec: 5.3 &quot;Finite Wings&quot;]
And interpreted thus,

Vortices have rotational energy which comes from propulsion. This additional requirement of &quot;Thrust&quot; can be balanced with Induced drag.

And this makes me question, how gliders form vortices when it does not have engines? Or even single mounted engines in prop planes that do not have engines on wings?
Could you see the vortices created by the glide of owl in the video here and here?
Also, if the phenomena of vortex is not due to engines than why there are four vortices in this famous image:
The vortices that you are referring to (I think) are wing-tip vortices, a product of the wing generating lift.  Since glider wings do generate lift (due to the airflow over the wing) and are propelled (without engine created propulsion) wing-tip vortices are created. Single engine airplanes also create wing-tip vortices since lift is being generated (aided by propulsion)
The jet in your photo is showing &quot;vapor trails&quot; or &quot;contrails&quot; from condensation (from the engines' exhaust) and are not wing-tip vortices.
I'm pretty certain there are a number of engineers on ASE that could provide a more technical answer, but the bottom line is the engines of an airplane do not create vortices (in the context of wing-tip vortices that I believe you are thinking of).