While I agree with the sentiment about the $3 luggage locks, I think it's still important to discuss that the $3 luggage lock doesn't work (especially if it's advertised to work). Some users might have the expectation that it does work.
On the more expensive devices, while I have a limited sample, my short career in IOT security has shown me that your $100-$300 devices have pretty serious security implications.
And I think there are a couple reasons why this is the case:
Atleast some (most?) of these products are being built by average developers with average exposure to security, so like other areas of tech, should be just as vulnerable as everything else.
IOT is a young industry, so you don't have the same set of best practices and common code that you can leverage. Ever wanted to encrypt sensor data, on a cpu that's designed to operate for a year on a coin battery? Turns out you can't just run openssl and TLS to secure that low power wireless connection. And that sensor might be the one telling you're security system to trigger.
Hardware is a super competitive market, so when it turns out you're basically selling every unit at a loss to try and gain market share, it doesn't leave a huge amount of room to invest in security best practices vs. get it done and shipped. You know that wireless sensor that detects when you're home and changes you're settings, well it's basically broadcasting to the neighbourhood whether you're home or not. It's a theoretical problem (every problem is until it isn't), that someone could use that against you, so do we worry about that, or do we worry about optimizing our code so that the battery doesn't have to be changed every month.
Please keep in mind, I have limited exposure, but in my experience working on this, I think unless companies can prove they're actively investing in security (and not just saying they care about security), we should be suspicious. I can see why the industry as a whole could be failing to protect it's consumers, and probably deserves a poor reputation for security.
And because you don't hear some researcher talking about product x, doesn't mean that product doesn't have abysmal security. A friend of mine keeps telling me, in her experience security researchers on average are cheap, so they're not going to look at the $300 lock, when there is a $3 alternative to pick apart.