fog install

i went to a shop today to get my PIAA fog lights installed....the guy told me that it will be very flimsy when it is mounted and made vibrate when the car is going fast, or even fall off if it hits something...told me that it's the car doesn't have any metal plating or anything to hold it securely except the plastic bumper part...is this true?

if i were to get a set of used GTS fog lights would there be a mounting bracket that comes with it???