Privacy laws vary wildly. In the US, "one-party consent" is common for audio, but is generally allowed only where there is no expectation of privacy. In Europe (GDPR) and parts of California, recording a public sidewalk without a permit can actually get you fined.
If a manufacturer has weak security protocols, hackers can hijack camera feeds. There have been numerous documented cases of "camera-napping," where bad actors gain access to interior cameras, sometimes even using the two-way talk feature to harass residents. hidden camera sex in ceiling fan mms videos 8 best