Gear and gear setup can also make bilaterals tricky - or even impossible.
I really do believe that this is something that shooters should consider, however, I would strongly advise those who want to look more into these skillsets to get proper instruction from a vetted source prior to attempting these skills,
particularly live-fire.
FWIW, the old Magpul
Art of the Dynamic Handgun DVD series did a pretty reasonable job getting into this on the second disk, but even so, there are finer points which were covered in "live" class (I unfortunately have yet to be able to attend a Magpul class, but I did take 6 days' worth of handgun - both HE01 and HE02 [now "Handgun Elements Theory"] - with Chris Costa in 2012, as a part of his then-new Costa Ludus outfit) but were either not covered in-detail or were completely not a part of the DVDs. Nothing comes close to beating having a real-live instructor there with you, to help you and give you pointers.
Also, as with everything else, there are multiple techniques that can accomplish the same goal. While the techniques covered in the Magpul DVDs are valid and serve as a great foundation, remember that there are others out there that are also worth learning.
As more and more folks come to realize the need for better training (thank you, Mr. Jack Wilson, for pushing the importance of training and practice to a national audience!), my hope is that this type of more advanced skill will be taught appropriately to more and more shooters. 10 years ago, it was rare to come upon a training class that offered such opportunities, and it was specifically towards these concerns that I decided to sign up for those Costa Ludus classes, particularly after seeing AARs such as these:
https://www.calguns.net/calgunforum/showthread.php?t=522232 (post number 8 in that thread, for example, shows Costa performing a demo of one of his non-dominant hand draw techniques). Fast forward 5 years down the line, and there's now a class locally, taught by a well-vetted and highly regarded instructor, sponsored through one of my state's 2A-nonprofits that also specifically target these skills.
It matters for long-gun, too, of-course -
^ That thiccboy is me, bumping over to my non-dominant shoulder to shoot under a vehicle, at a 1" stake that simulated the shin bone of a threat on the other side of the vehicle. (Similar to the Magpul handgun DVD series, they also put out a two-volume [6 discs total, 2 for the first, 4 for the second]
Art of the Tactical Carbine and single-volume [2 disc]
Art of the Dynamic Shotgun, both of which also covered bilateral and injured-shooter skills. For pure manipulation and marksmanship skills, the Panteo Productions
Pistol TAPS and
Carbine TAPS [Pat McNamara] DVDs offer excellent bilateral drills.)
Similarly, being able to shoot and move or shooting-while-moving is also another set of skills to practice. And as Larry Vickers pointed out, for those of us who do not hunt, any chance that we can get to shoot at movers, we should. These are another two big reasons why I try to attend training classes - luckily, two of the schools local to me offer moving target systems.
Great post,
SMSgtRod!