How can I use launchctl to send a signal to a service?

As you can already see in the text below and screenshot of the terminal, whenever I try to send a signal to a service I have given Not privileged to signal service. and Could not kickstart service "com.apple.accessibility.heard": 1: Operation not permitted.

~ % launchctl kickstart -k gui/$(id -u)/com.apple.accessibility.heard    
Could not kickstart service "com.apple.accessibility.heard": 1: Operation not permitted
~ % sudo launchctl kickstart -k gui/$(id -u)/com.apple.accessibility.heard
Could not kickstart service "com.apple.accessibility.heard": 1: Operation not permitted
~ % launchctl kill SIGHUP gui/$(id -u)/com.apple.accessibility.heard     
Not privileged to signal service.
~ % sudo launchctl kill SIGHUP gui/$(id -u)/com.apple.accessibility.heard
Not privileged to signal service.

Does anybody have an idea to overcome this issue? Edit: Just to be clear, I am trying to start Background Sounds feature from terminal

defaults write com.apple.ComfortSounds comfortSoundsEnabled -bool YES
defaults write com.apple.ComfortSounds lastEnablementTimestamp $(date +%s)
launchctl kill SIGHUP gui/$(id -u)/com.apple.accessibility.heard

Second Edit: I have solved my problem using the following commands, but still wondering **why cannot send signals to services?** defaults write com.apple.ComfortSounds comfortSoundsEnabled -bool YES killall heard launchctl kickstart gui/$(id -u)/com.apple.accessibility.heard