Examination of applications with matter in more than one art unit/classification?

Question

It is not uncommon for patent applications to relate to "systems" comprising subject matter relating to more than one examination art unit and/or classification.

Consider a self-driving car patent application that discloses novel steering and/or braking control methods based on novel analysis of sensor (e.g. LIDAR) data, e.g. with claim:

A method for automatically decreasing stopping distance of a vehicle, comprising: (a) projecting a structured light pattern from the vehicle; (b) detecting a non-transient obstacle external to the vehicle; (c) automatically pulsating brakes at an increasing duty cycle; and (d) automatically oscillating steering about a stopping axis.

In this case, there could be in-depth technical details relating to both vehicle control and wireless sensing. However, it is unlikely an examiner would be proficient in both these technical areas (if not for this example, then at least for more complicated examples).

Do examiners just "do their best" despite potentially not being able to apply appropriate obviousness and/or enablement arguments, and probably performing a poor search? If so, are these types of patents more vulnerable to invalidity challenges due to weak examination?

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EDIT: Thank you for the answers so far, though they appear to focus on the "easiness"/difficulty of an art unit. The question here is how to deal with a case where an examiner is not technically equipped (i.e. cannot represent and/or play the part of a PHOSITA) for at least one of the technologies he/she is examining.

Answer 1

Yes, examiners just try to do their best. Some practitioners deliberately obfuscate the field of their invention in hopes to get an Examiner that will be more friendly (inexperienced) to the technology.

EDIT to address the concerns of questioner:

Because the standard is a Person (singular) Having Ordinary Skill in the Art (singular), the USPTO chooses the primary art field and can only combine the techniques that are within reach to a person in that field. Granted there is wide breath of what would be in reach of that person but this is not always the case. For example, if there's some advanced technique known to the top chefs of Lebanese cuisine that could be useful to an astrophysicist designing a new telescope, there is a strong case that combining those two fields is outside the scope of a person having ordinary skill in the art. In other words, the examiner only must act as an expert in the primary technology.

Answer 2

This would probably depend on the Art Unit the allotted Examiner identifies with and would be very subjective depending on the expertise of the Examiner. Some of the related concerns are analysed here: http://www.ipwatchdog.com/2015/05/21/hardest-easiest-art-units/id=57864/ These Are the 20 Hardest and Easiest Art Units