The analogy is problematic, and worse, it is somewhat in error. But we can deal with it for a minute.
FIrst, Docks do deteriorate. One of the few constants in the universe is the effect of Atrophy. That is the way things break down. Docks are particularly susceptible to this effect. The cost of maintainance is factored in to the business plan of most people with enough brains between their ears to actually start a business. So our Dock Owner has been setting aside money for some time to manage repairs.
The cost of those repairs would probably be at least the equal to the annual docking fee of one ship in your scenario, and hiring riff raff, who do you think anyone would hire? Folks that you would consider riff raff almost certainly. Construction is hard and dirty work, and folks involved in it generally speaking don't have the table manners of the elites on Masterpiece Theator.
Now, the way tax breaks really work is like this. You have a business, and it will employ a hundred people when you set up your new distribution plant. You need to place it within 100 miles of Charlotte. You start examining locations, and you tell these various towns and cities that you are doing this to find a suitable location. You want to know about trash costs, property tax costs, and a lot of other factors that will go into your estimates.
The cities want you there, in addition to bringing in the business, most of the people you hire will be local. They will see an increase in their tax revenue, even if they cut you a break. You see, not only will the employment taxes go into the city coffers, but those employees will buy things with that money, and that goes towards the sales tax income that the cities need for things like police, schools, fire departments, and a host of other things.
So the City does their own math, and comes up with some estimates, and whamo they announce that they will give you a break on property taxes for twelve years if you pick their city. The location you've chosen will be near the freeway, and has good access to rail lines as well. It's a good location, but there are others that are just as worthy. The twelve years of reduced property taxes seals the deal.
For that twelve years the city still comes out slightly ahead on the other taxes I mentioned. Diners crop up around your place for the employees, and truckers, a Truck Stop is built to service the drivers and trucks. All of these other businesses pay taxes, and make their money off of your distribution facility.
It's like a night club that offers Ladies Night. No cover charge, and two free drinks per lady. The night club will get the ladies in, and where there are ladies, the men will follow. The Night Club comes out ahead because more people show up, and most people including the ladies, have more than two drinks.
Or a bar that offers happy hour with half price well drinks. Those happy hour specials don't really cost the bar money, but do make money on the overall picture as the drinkers stay for a drink or two past the happy hour limit.
Many people like yourself, denounce such deals, despite the fact that they generally speaking end up bringing in a lot more money than they cost. Perhaps you don't like the ladies, I don't know, and don't care. But these techniques have been used for generations with success. Grocery Stores offer Buy One Get One Free on some select items. Even if you buy every single one of them, and nothing else, most people will buy something else, and the store still makes money.
Now, we've addressed your terrible analogy, and used much better ones to examine the question of tax breaks. I'd ask if you had any questions, but I'm sure you do, and I doubt I can help.