These devices should be using multiple microphones so that they can tell where sounds are coming from, and during setup they should be shown the location of the TV and exclude any commands coming from there.
If it reacts to any voice, it's unusable for anyone with kids. Shopping really has to be locked down to authorized people's voices. Is it even legal for kids to order stuff on the internet?
In Germany, all children of any ages can buy anything with previous approval by the parents. From age 7 on products costing less than the monthly pocket money cna be bought with approval after buying, from age 14 on all products.
So, as a result, you might have a 4 year old child ordering something online, and have to honor the order (just as 4yos frequently are sent to fetch bread from the neighbourhood bakery).
Obviously, cultural values affect this heavily — while in Germany and Japan this is normal, in many areas of the US people below 16 are not expected to act on their own, or buy things, so it can be obviously different.
Though in Germany, products sold to children not meeting the criteria (i.e. being bought without the approval of their parents) can be returned, since law places the fault with the seller.
As well as the fact that any product bought online can be returned within 2 weeks without explanation.
So there's an incentive for the seller there to limit accidental purchases, since those will likely cost the seller more than the disgruntled parent, who at most has to pay for shipping the product back and forth.
In the US, the 4 year old could be taken away from the parents if they allowed him to go to the bakery alone, and the parents would be lucky to avoid jail.
