Low voltage can mean many different things to different trades. Low voltage to an electrician is below 480 volts. This is why the NEC uses the term Limited Energy.
Also, low voltage is not exempt from licensing or permitting! It does depend on the AHJ which is usually the state.
State Licensing Guide 1-26-09.pub
For example, no licensing or permitting is necessary in my state of Michigan for low voltage unless burglar alarm or fire alarm is involved.
Many other states do, in fact, have licensing and frequently licensing/permitting. Hawaii, Florida, Maryland, Minnesota, Washington,and Oregon are all states where licensing/permits are required.
If you are installing 10 cameras on a private business you are unlikely to draw any notice from inspectors. However, if it's a multi-million dollar project where other trades are performing work (particularly fire alarm) be prepared for fines.