[simplecomplex]

It had already been attacked and was full of international guests. In the capital city. 4-5 guys should not be able to take complete control of the hotel with no heavy weaponry. That means security is deficient or non-existent.

[ricardobeat]

What kind of daily security setup can protect against 5 gunmen with AK47s?

[ip26]

You don't necessarily need to meet them head-on & emerge victorious, just delay them long enough for backup to arrive and/or deter them, again by showing that you will delay them.

[thecrazyone]

Why aren't autonomous or remotely controlled rovers, or turrets ever installed?

[vsl]

Armed and trained security detail/guards.

[runjake]

"Should not be able to take complete control"

Sure, in a normally-functioning country with available leadership and logistical resources. But that is not Afghanistan, at present.

That was my whole point.