Does oil oxidation create trans fats?
First, a little chemistry primer on what unsaturated fatty acids look like (this is petroselinic acid):

By Yikrazuul (talk) - Own work, Public domain, Link

You can see the double bond near the "middle" of the molecule. The "rest" of the molecule is attached to the same side of the double bond axis on both ends, making this a "cis" fatty acid. Rotation around double bonds requires a relatively high amount of activation energy, so this "cis" configuration is stable, at least at low-ish temperatures.

An example of a "trans" fatty acid would be elaidic acid:

By Benjah-bmm27 - Own work, Public domain, Link

Here you can see that the molecule continues on opposite sides of the double bond axis ("trans"). At higher (e.g. frying pan) temperatures, unsaturated fatty acids more readily isomerize between cis and trans, and since trans is energetically favorable, more unsaturated fatty acids will be in their trans configuration after being heated to a high temperature.

So to answer the question(s): 
No, trans fatty acids are not generated by oxidation, but the same conditions that favor oxidation (high temperature) also favor the generation of trans fats from cis fats.
Also, the bacteria in the digestive tracts of ruminants (cattle, sheep, but also deer etc.) produce a significant proportion of trans fatty acids.
In addition, the simplest (and cheapest) industrial processes to saturate ("harden") unsaturated fats produce a relatively high amount of trans fats. So yes, not adopting other processes can be economical, if this can be considered "intentional"...your call.

A more extensive explanation can also be found in the accepted answer to this question:
Does preparation of food change the nutritional content with respect to fat type?