Can bus is more of less locked down, while any one can get the tools to decode the data off the bus, you have to jump through some hoops to get the standards that begin telling you what does what, and many, many many! more hoops if you are interested in a manufacturer or model specific piece of data on the bus,
for that kind of stuff, being bold enough to arrive at a primary dealership / service site for that brand, wearing an orange vest and work clothes and talking to a supervisor can get results (I work with vehicle logging devices that use can-bus) and so far for 6 brands this has been the only way i have managed to get anything. 2 of the brands do not even allow printing off of there chained to the wall service computer, (camera phone...)
For even ride on mowers i have seen the same, a European brand would go into limp mode if it went a few months past its service date, that could only be reset by a dealer tool, that person had the smarts to hook up a can-bus sniffer to the diagnostic port and logged everything the dealer tool did, took him about 4 weeks of brain bending but he found how the new date was set, and from then on has been servicing them himself,
Another thing i have seen is AD-Blu systems and would imagine it is common to AG aswell, there are atleast 2 brands of buses going around that have very poorly made level sensors (internally leak), i've since repaired a number of them, but looked into what it would take to disable the system, or atleast replace the level sensor with an aftermarket fuel sensor, and in both cases there was a few hundred thousand dollors fine for an individual to tamper with the system, not disable, just tamper with.... and closer to a few million for a company to tamper with the system,