>What's the excuse for the hotel not having any security?

https://ewn.co.za/2018/01/23/afghan-hotel-attack-stirs-fresh...

"KABUL - A bloody Taliban raid on a high-end hotel guarded by a private company in the Afghan capital ...

[...]

“There were 15 guards on duty at time of the attack and none of them engaged the attackers,”

It's a hotel in Afghanistan, a country presently immersed in turmoil.

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.

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

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.

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

Armed and trained security detail/guards.

"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.