> As a rule, ships will operate near objects such as planets, asteroids or nebulae. These objects provide plenty of opportunity for cover and ambushes.

Maybe in science fiction.

The main problems you have are:

1. Space is big and mostly empty. A few hundred probes could cover every blindspot in a solar system.

2. Going anywhere requires venting hot gas that's highly visible. Even small ion drives are detectable light minutes away with current technology.

> There is also the possibility of minefields and other unmanned devices that can easily be shielded from detection

Shielded how, exactly?

Also, how are these unmanned devices going to get close to their targets? Space is big, so a ship isn't going to blunder near one by chance. Perhaps if you knew the ship's route ahead of time, but then even a small randomizing factor introduced into the route would prevent that.

> we tried this with drugs, terrorism and copyright violations - all of which are still going on despite the massive amount of resources employed to eradicate them.

Drugs, C4 and digital files are small, easy to hide, and relatively inexpensive.

A spaceship is none of these things.