"It promises 4K resolution and three cameras for a price that suggests neither will work well."
The '4K+1080P' claim is marketing shorthand. The system will likely only achieve an interpolated 4K resolution with the front camera running solo; performance with all three channels will be substantially lower, compromising the quality of your video evidence.
This is for the driver on an absolute shoestring budget who needs the legal check-the-box coverage of a third, interior-facing camera for ride-sharing. The rock-bottom price, which includes an SD card, is the sole compelling feature.
Anyone who needs reliably clear footage for insurance claims or identifying license plates should invest in a system from an established brand. The engineering compromises necessary to hit this price point make it a poor choice for anyone prioritizing reliability or actual image quality.