Right, but its not a "'30 minute delay" if you schedule construction to start at 1230 once guests are largely gone instead on at midnight. I mean, if you're going to go through all of the trouble to avoid hammering in the daytime so guests won't hear it, then why not factor in that extra half an hour to the schedule? And jackhammers are not "a little noise"...
There is a reason the rides don't shut down abruptly at close and continue to take guests who are in line. There is a reason Main Street is open late (aside from merchandise $). There is a reason the supply trucks don't start driving around the park right at midnight. This last hour or so is still a legitimate part of the guest experience, and if you're going to make the effort to avoid doing construction during this guest experience, as Disney should, they need to do it during the full portion of the guest experience, and not just part of it.
It is not as easy as you make it out to be first of all supply trucks are not allowed on stage for safety reasons and because Disney has a third shift that is already scheduled and budgeted to do after hour work for the whole resort.
Construction like what is being done in the fantasy fair area is mostly done by outside contractors. Half an hour or even an hour might not seem like a big deal but when it comes to construction projects it could mean the difference of thousands or millions of dollars.
There is only so much time that the park is closed without guest inside. during the summer the hours are even shorter since the park stays open later. Let's just take in account the summer months of June, july, August which is a total of 92 days. Your suggesting that they wait till the park clears up which is normally an hour after park closing. That will account for 92 hours extra of construction time to be added to the project timeline. This project is suppose to take several months to complete so waiting that extra hour could add weeks of construction time.
Yes maybe they could have extended the completion time for the project to a later date but that would only increase the cost of the project. Everyday that is added to the construction project is thousands of dollars extras that are spent. Demolition Equipment has to be rented for longer time, Worker insurance has to be extended , facilities for the construction workers have to be kept longer. Etc etc.
Now add to that lost revenue, a project that takes longer to open earns no money. Those extra months of construction just so that it makes a small group of guests happy at closing time causes revenue that comes from merchandise sell to be lost especially in a project like this which will bring in lots of sell in Princess merchandise. Lost revenue and extra construction cost eventually means that adjustments have to be done to balance the books. In other words other projects are cancelled or postponed until funding is found for them.
Now let's look at something else when it comes to guests experience, only a small group of guests are experiencing the noise and lights at closing time but thousands more are experiencing a closed of area with construction walls that creates traffic nightmares especially at night during fireworks. It makes more sense to finish the project as soon as possible and only inconvenience a handful of guests.