Cal-Star was the first company to go into tickling videos in a big way in the late 1980's early 90's. Why? Money. They found out they could sell tapes. So tickling got tossed into the production mix of bondage, S&M, watersports, and spanking.
Harmony found out the same thing, and added tickling to thier bondage, spanking, S&M, DiD, and superhero lines. There was money to be found in the fetish.
FM came next, tickling fit well with their foot fetish oriented line. So they added it.
THEN came the independents. Solefully yours, MTP, Bloodstone, ANA, Rock, TC, FP, SilverCherry,and more. These are the folks who got into it because of a like... you'll need to ask them as to why each individually. Good luck 🙂
And this is a very simplified retrospective. Companies left out were due to my faulty memory, or desire to keep it simple. No slight intended.
Myriads