People will be much less likely to make those claims if you clearly state where the data is being stored. This article + their project page doesn't mention anything about privacy.
People need to ask the question before making assumptions. In the case of Apple, they said it directly in the presentation of FaceID as well as TouchID IIRC. Yet people made these claims anyway. For this project, they also state it clearly on the page:
> Are my images being stored on Google servers?
> No. All the training is happening locally on your device.
Where is it clearly stating that? I couldn't find anything in the linked article + the github repo + teachablemachine.withgoogle.com
But I do agree people need to ask the question before making assumptions. Sadly, the two popular mindsets is either to not think about privacy at all, or believe that everything is infringing on your privacy.