We're paranoid about not running your car's battery down. When the ignition is off, we consume less than 1 mA. By itself, the Automatic Link would take 3-4 years to drain even a cheap battery.
Let's say your average battery has 40AH. That means it can provide 1A for 40h (or better, the product time(h) x current(A) = 40 for a charged battery) @ 12v
If your lamps consume 24W (I'm guessing), that's 2A, it means it would go from fully charget to nothing in 20h. But of course, your battery is usually not 100% and you need a certain battery capacity to start the engine.
Even if the consumption of this device is 1W while idle (which is really an exaggerated value), the device uses around 0.084A and the battery would take 480h to go from 100% to 0% (or about 20 days)
My guess is that an unpowered car uses more than that by itself, so this dongle is not an issue, unless you're leaving it unattended, you can unplug it but will probably run out of battery nonetheless.
I don't think most car batteries are dead after twenty days of not driving, and, as you said, most batteries aren't always fully topped up.
It's possible to build it to not use excess energy.
Personal anecdote: Last year I would not use my car for long stretches (between 2 and 3 weeks), as I was traveling. 2 weeks is doable, 3 weeks I'll be certain to have a dead battery on arrival.
At 1mA of current draw, this device is definitely not a problem. But the idea that an unpowered car uses enough power to drain the battery in less than a month is clearly ridiculous.
In a climate where 32F may be the highest temperature seen for months, a car sitting idle for two weeks can definitely be in danger of not starting due to the battery not being able to crank the engine after being cold-soaked at -20F all night.
If the battery is showing some age, and/or didn't go to 100%, less than a month is typical (depending on the accessories as well: alarm, stereo - some uses standby power, etc)
An older battery surely won't do as well, but then it'll do even less well with an extra 1W draw hooked up. No matter how you slice it, a load that will drain a car battery in good condition in 20 days is a pretty big load.
If you switch the alarm on, that budget increases to something like 120mA, but you'll kill the car inside a fortnight.
Most other electronic components are sub-100uA