it happens, but not as often as you'd think

so my advice when you're travelling:

• assume your bag is going to be whacked with a baseball bat, it goes through hundreds of metres of conveyer belts to be checked, weighed, screened, x-rayed etc. between the check-in desk and when it reaches baggage handlers to be loaded ULDs and on to the airplane, as it moves along the conveyer, it's hit down a chute to ensure it goes to the right pier operated by the right airline to be loaded, called a glidepath, this is most likely what broke something in your bag, as you can imagine there's hundreds of bags that needed to be loaded within a short amount of time
• the best bag you can buy is hard-sided Sampsonite bag, don't buy a cheap as shit bag with handles that will fall off or zips that will burst open, there'd be nothing worse than seeing your shit flying everywhere on the tarmac as it's being loaded (believe me, I've already seen it happen)
• the whole spiel in Fight Club about vibrating luggage, how modern bombs don't tick, they vibrate, it's 100% true and I'm required to report it if your luggage is vibrating, 99.99% of the time, it's either an electric toothbrush or one of those razors with batteries, and yes, every once in a while, it's a vibrator!
• no, I have never been through your bag, nor will I ever, nor have I seen anyone go through a passenger's bag, I don't know you from a bar of soap, there's hundreds of CCTV cameras, plus I simply don't have time, and unless something is leaking, vibrating or stinks, I couldn't care less what's in your bag
• I go through the exact same screening process as passengers before I start work
• how is luggage lost? most of the time, you checked in at the very last minute, there's about 10-15 minute gap between when you checked in and when it reaches baggage handlers, when your bag comes down the chute and your flight left five minutes earlier, most of the time, baggage services will just put your baggage on the next available flight, if you're lucky, your baggage might reach your destination before you do
• what causes delays? if a passenger comes of the plane (i.e. sick, arrested, freakout about flying ala Marge Simpson - it happens), baggage comes off too, thank the events of Lockerbie in 1988 for that, new tag technology makes it easier to find bags, but sometimes we'll need to take bags out to find offloaded passengers bag(s)