One big bolt is missing from this plate underneath, it's not a problem, is it??

[Gilles]

Originally Posted by Homeoboxter

This was done by a reputable shop for a lot of $$$ so you would expect them not to leave out random bolts, especially one that play a role in the car's structural rigidity.

Homeboxter, since the OP stated that the shop charged the owner for an alignment afterwards, it seems that the missing bolt, somehow got loose and fell from the car 'after' it got aligned and delivered to the customer.