Uh, have you read the part in my comments where I said that they're morel likely to be honest about it? Having a short errata or no errata at all doesn't mean the product is flawless. It could be that they don't know all the faults yet, or aren't sharing them, or both.

For ST it could be that they seem to be the most popular cheap ARM microcontrollers for hobbyists and consumer products, so it's easier to find faults in them since so many companies use them, similar how the most used pieces of software also have the most vulnerabilities reported on them.

Also, maybe ST was not a great example on my end, as they seem to have an obsession lately with outsourcing and farming out everything to the cheapest offshore location possible and penny pinching to the extreme for their consumer oriented parts. I don't blame them though, competition in the generic ARM microcontroller market is cutthroats and margins are slim and salaries are low and your major customers (Sony, Apple, Samsung, LG, etc) keep putting the pressure on you to lower your prices or threaten to look somewhere else.