The Luxury (ne: Luxurity score) can be seen as the total value of all structures and decoration you have on your Island.
From ~v1.2.7 the developers renamed this score from the Luxurity Score to the Luxury Score, which I think is quite sad, as they obviously bowed to the illiterate who thought this was a simple spelling mistake, when in fact the term "Luxury Score" really does not explain properly what this score represents, wheras "Luxurity" is a proper and meaningful word - as in:
> Luxurity is made up of two parts. “luxury” which means “decorating”, and “ity” which means “having the tendency” or “willingness”. (Moein, 1984: 1032). In other words, luxurity means willingness towards artificial beauties.
When you build or upgrade a structure, your Island's Luxurity score is increased with the same amount as the costs for that construction or upgrade were in $. So an upgrade cost of $ 1,000 will increase the Luxurity score with 1,000 points. Demolishing a structure will inherently decrease your Luxurity score with the amount of points the demolished structure was worth. Moving structures into the warehouse does decrease the Luxurity score, putting them on the island does increase it.
For the structures that cost € to build the Luxurity score increases with ~15,000 per € (differs a little per structure).
It is believed that the Luxurity score influences the amount of tourists that comes to visit your Island, i.e. the higher your Luxurity score the more tourists you can expect. So to increase your Islands Luxurity score you should build more and more expensive structures. According to someone's notes on Awards 137-143 - the number of tourists / visitors awards are triggered purely by increaesd XP, and so have absolutely nothing to do with the Luxury / (ne: Luxurity) score. Assuming that is true, in theory you could have just one Hot Dog and one Cabin and one Windmill built from your tutorial and just collect income from those 2 structures for a year and never increase your Luxury score, and yet still get your tourist awards as your XP increases ever so slowly.
The Luxury score is therefore quite pointless except as a status symbol for you to know how "valuable" your island is, and the table which has never been updated is even less pointless - unless the wikia could hot-link cells to other pages so the individual cells will automatically fill in and automatically update, otherwise the "Luxury" values are exactly the same as the Constructing and upgrading costs and time table except the Piastre building purchases giving roughly 15,000 Luxurity per €, and the little it differs is not worth caring about for a meaningless score.