Matrix got it a bit wrong; the machines aren't interested in our body heat, they're going to put us in the goo pods and force use to watch adverts 24/7
Some not so reliable sources I found:
https://www.reddit.com/r/matrix/comments/q2i0by/is_it_true_t...
https://www.reddit.com/r/plotholes/comments/11khig/comment/c...
Source? Like 20+ years of ubiquitous surveillance, tracking and micro-targeting.. and yet non-pet owners still get ads for dog food, males get ads for feminine hygiene products, single people are offered deals on family vacations, and people who just bought a car get car advertisements for the next 3-5 years which only taper off when it might actually be time to buy another car.