$10 for a full meal (not including tax and tip) is probably unrealistically low for the bay area. State and city minimum wages are increasing (SF is $14/hr and they have other mandates like healthcare coverage) so food and restaurant prices are going up (many meals seem to be in the $12-15 range, approaching $20 w/ tips). Many restaurants are closing, and are exploring alternate business practices, like pop-up stores, mandatory/included tips, and food trucks instead of fixed locations.
Forcing workers out of the office without their consent seems disingenuous. Travel expenses can be a burden, and such travel can cause disruption in areas where rideshare services may be flaky and increasingly dangerous to passengers.
The increase of food trucks is, on average, perhaps providing office workers with less nutritious food options which they have less control over (especially compared to big tech office cafes).
Increasing use of outside food establishments increases the 'lunch commute', adding to already-insane traffic, pollution, and stress for workers who already commute too much.
On the plus side, this may create increased demand for lunch spots, however it is increasingly difficult for them to operate while providing affordable prices for healthy food, and I don't think the increased demand would truly offset this effect, but rather could have negative effects on the workers caught in the middle.