In a past life I was an embedded designer, and I think your observation is spot on. While the libre enthusiast in me would love to be able to inspect and possib

In a past life I was an embedded designer, and I think your observation is spot on. While the libre enthusiast in me would love to be able to inspect and possibly modify bona fide firmware, I do respect that say tweaking the code on a power supply or motor controller is fraught with hazards (you want to use a debugger? while the microcontroller is stopped, your circuit cooks. you want to use printf to a serial port? the additional cycles make your circuit cook ...) But there are tons of companies abusing the term for software that is actually being continually updated, and/or isn't hardware critical at all (eg Intel ME). The use of "firm" here is entirely prescriptive, for the manufacturer's business desires to lockout end-users, rather than because the code is akin to fixed hardware. A simple test might actually just be the desire to modify/repair. Nobody wants to really dig into a power supply controller unless it's doing something very broken that needs be fixed. Meanwhile what creates the most e-waste is the ending of software updates, which are most certainly not firmware.