Bike Anti-Porn - When Things Go Wrong

Those aren't Stock Trials bikes, they are OTP Mod Trials bikes. Stock vs. Mod means different rules, not a distinction between tailored and ready to wear. Stock bikes have multiple gears and a saddle, Mod bike are not required to have either.
Sorry but you are wrong.

Mod and stock are terms used to describe wheel size.
26" = stock
19 and/or 20 = Mod.

There's also the new breed of 24s which are classified as Stock for competition but taking a long time to catch on (mainly as the first time anyone came close to winning anything riding a 24 in the stock category another rider complained so they were disqualified)