[kjdndisneinj]

The 330V is for sure a misprint. It doesn't look like they have the insulation for a high voltage motor, so my guess would be 30/33V @15A. Reading the linked spec sheet confirms it's in the range. That would put it much closer to a cordless drill motor. (450W, not 5kW, which is obviously impossible on 120VAC/15A)

[TD-Linux]

I actually think the insulation is adequate for a line voltage motor. You can also see that the brush holders were heavily modified (and kinda ugly) in the Juicero motor compared to the spec sheet [1], likely due to the higher voltage.

Though the most telling is that the only isolated supply is the 5V Meanwell, the whole bottom half is at line potential as evidenced by the lack of transformers and the optoisolators right below the Meanwell supply (for controlling the H-bridge below).

One thing that still seems to be missing is active PFC - it was implied by the article, but I don't see enough components for it. Maybe it's just a rectifier into 170V/330V, and the in the case of 330V they drive the motor at half the duty cycle.

One other question was "why not a series-wound motor?" It was pointed out to me that one potential reason is that a series-wound motor introduces 60/120hz hum and vibrations, and maybe they found the noise objectionable.

[1] http://en.jiaai.cn/products_detail/productId=65.html