You hqve a good point here. For security cameras yes anyone can do it. For alarm systems where is involved lives, I am 100% people we love to know every thing works fine and it will be working agter is installed it, also people forgot the liability point of view of insurance. If you install by your self a new set of brakes in your vehicle to save some dollars and you got an accident and the accident was on investigations and show at the end it was because you forget to place the safetu device and the insurance found this issue and ask where you do your breaks so we can go and claim every thing we are paying to you…you will say, I did it by my self. Where you thing the investigations and suspicious will go. More and more people install alarms system by it self and more and more you see them in courts defendant their self from insurance claim they did it in porpuse, insurance think they did that wrong to claim millions.