how can you trust courier services

Hopefully, the package is marked as Fragile. Otherwise, if there's a fence, it all depends on the person delivering the package. If they're lazy and they don't care, they'll chuck that package over the fence without a care in the world.

But hopefully, the person bringing you your Amstrad computer will care enough to set it down gently so nothing gets broken.

I would be livid if a delivery driver threw my package and broke stuff.

I'd say your absolute best bet, would be to be at home, so that you can take the package when its delivered so that way you know nothing is broken. And, you can get the delivery drivers name or truck number. That way, if something is broken, you have a way to contact the delivery company and tell them so and so damaged your package.

You can’t be sure. Such things do happen. I know someone who ordered a new I-Phone in November, first he gets told there will be a delay. It was about the time the Apple workers at an IPhone plant in China were striking. Several weeks went by and he didn’t get his phone and he contacted UPS because it was supposed to be delivered to the UPS store for him to pick up. Finally he got his phone, I think someone had stolen it before it got to the store.