They can be used in landscape photography as well when a perfect steadiness of the camera is required. Thry can also be used to trigger multiple flash lights. They emits in radio frequency waves (RF) so no cable binds the emetter to the camera which can make life easier in some situations.
When it is not possible to perfectly camouflage oneself or the shooting site doesn't enable one to build a hideout, the use of these little gadgets to control the trigger becomes very convenient. It's just necessary to know the exact position of the subject. For example the preferred roost of a bird or the entrance of a burrow.
The advantage of this system is that it emits in radio frequency. These waves are not stopped by a cover or a tree, unlike infrared control. It is obvious that there is always the possibility of using a wired remote control, but the distance to the camera will be proportional to the size of the spool of coil...
By radio-frequency waves, the trigger can be done about twenty metres from the camouflaged unit as opposed to an infrared transmitter that requires the receiver to "see" the transmitter.
The price to quality ratio is excellent because they are quite affordable and their construction is well made. The parts that have the most mechanical stress are in metal which guarantees prolonged use.