Because they dont have a time-tested strategy to rely on.
communication
3 Pack Dog Doorbells, Pet Training Bells for Go Outside Potty Training and Communication Device Large Loud Dog Bell Cat Puppy Interactive Toys Adjustable Strap Door Bell (Pink)
Adjustable Length: Our dog doorbell comes with snaps, easily adjusting the length between 30″” and 33″”. Works on different kind of doorknob, handle or hook that you want to affix it to. Easily mounted, can be hung at any level to accommodate pups of all heights.
Khptop Motorcycle Helmet Bluetooth Headset 500meters 2 Riders Bluetooth Helmet Intercom Headset with CVC Noise Sound Quality Speakers Communication Systems Motorcycle Riding/Snowmobile/Cycling/Sports
Universal compatible headphonesCompatible and paired with other brands of headphones. Can match and talk to third-party Bluetooth intercom headphones. The motorcycle helmet intercom kit allows two riders to have real-time conversations within 500 meters (if you are riding at 120 yards or in areas with poor signal, it is recommended to use the earphone intercom function within 200 meters)