When corresponding with the vendors, the answer was always that the software provided the features that were lacking out of the box. In the second case, the box contained a leaflet referring to software, installation etc, but there was no CD in the box and when asked, the vendor had no knowledge of any software and asked me to search the web.
So what's going on here?
It seems that many of the vendors are box-shifters and have no knowledge of the products they are selling. They simply reproduce what the Chinese manufacturers have plastered over the boxes. These claims can only be taken as "what you can do in an ideal world with lots of additional software". It bears no relation to what you can achieve by plugging and playing.
What can you do?
The first thing to do is ask questions before you buy (unlike me!!). Ask if the webcam comes with drivers and what software is included in the box. If the answer is that there are no drivers or software, by advice is to pay a bit more for a webcam which does include them. It is just possible you might find something on the web, but the second camera had no manufacturer or model number to go on, making a search impossible.
In summary, if a webcam spec looks too good to be true for the price, then it is and you would be better spending a bit more, preferably with a specialist vendor who knows a bit about what they are selling.