People not in involved with the restaurant industry have inordinately high expectations of brand new establishments. For instance, the diner just opened for business a week ago and is still technically in a soft open. They have yet to roll out the full menu as it takes a little while to get all your vendor deliveries coordinated.
Until you open your doors, you can never be fully prepared for service. No matter how long you have to prep your staff, they are going to be flustered until a routine is established. These things take time and yet people expect everything to be perfect from the moment the doors open.
Here’s a tip: if a restaurant is brand new, wait about a month before visiting OR temper your expectations. If you walk in right away, know that your servers might not know the exact details of every dish and things will likely take extra time. The music won’t be dialed in quite yet, the kitchen is going to mess up more orders than they’d like, and the hostess might not have all the tables memorized.