Did the sensors in Star Wars universe not have the ability to scan for droids?

In Star Wars, when R2-D2 and C-3PO leave in the escape pod, the star destroyer operator says no life forms were detected. Given the technology in the Star Wars universe, I'm surprised they couldn't see that there were two droids, especially since they were both still active. If they were deactivated I could understand. Are there other instances of droids evading scanners in a similar manner?

Answer

If a high ranking imperial officer had been present, this mistake would probably not have taken place. Imperial troops and operators have had a history of being unimaginative throughout the original trilogy*. This is probably because they are usually acting on information provided on a need-to-know basis. It is likely that the mission objectives given to them say nothing about the theft of the Deathstar plans (a fact best kept secret!).

*Examples:

1. Letting the escape pod go.


2. Falling for the 'need some help here' call from inside the Millennium Falcon.


3. Ignoring small fighter assaults on the Deathstar (leaving Vader and his personal squad to engage them).


4. Trusting two unknown droids during a security breach.

And so on and so forth.