I bet you haven't heard
all the arguments. Here's one that came to mind when I read the actual text of the repair law as to why there might be two of those three exceptions.
For agricultural and forestry equipment there is already extensive California law dealing with them in the the California Business and Professional Code (BPC).
To wit, the "Fair Practices of Equipment Manufacturers, Distributors, Wholesalers, and Dealers Act" which is Chapter 28 of Division 8 ("Special Business Regulations") of the BPC.
Alarm systems are also regulated under the BPC.
This new "Right to Repair Act" is part of the Public Resources Code. It is is Division 30, Part 3, Chapter 8.6.
Division 30 is "Waste Management". Part 3 is "State Programs".
Chapter 8.6 was the "Cell Phone Recycling Act of 2004" so presumably is getting renumbered to 8.7, and the "Right to Repair Act" is being inserted right before that, after the "Rechargeable Battery Recycling Act of 2006" (Chapter 8.4) and a chapter called "Electronic Waste Recycling" (Chapter 8.5).
(Why is this done as waste management under the Public Resources Code rather than under whatever California's consumer protection code is called? I have no idea!)
It seems at least plausible that the exceptions other than the video game console exception are there because legislators feel that changes to how those things are handled should be done separately via changes to the BPC.