While there's no such thing as a "standard" restaurant chair, during my table-waiting days I've handled tons of these:

I know you can't see what the underside looks like, but it's burned into my brain from inverting these onto tables at the end of each shift. Beneath the seat, the front and side aprons are connected by little mitered pieces for rigidity. Those and the seat are the only unseen pieces of wood in the photo, so all in we're looking at 13 pieces of wood and 20 joints.

Portugese industrial designer Goncalo Campos prides himself on "finding simple solutions through the sound use of materials and production methods." His Babar chair, designed for restaurants and the larger contract market, replaces the ladderback design with just 9 pieces of wood and 8 joints.

Rather than being connected to their adjacent neighbors, here the legs are connected only with their diagonal counterparts. The chair is missing a leg in this shot, but you get the idea:

The Babar chair is in production by Italian furniture brand Cizeta and available in different heights.