The Phuket fleet is booked two different ways, and flattening that into one list would misdescribe the market. Above roughly thirty metres you charter a named hull with a named crew: this yacht, built in this year, with these people aboard. 2 of the listings here are that.
Below it, in bareboat and skippered charter, you book a model. Nobody sells you hull number 214 of a Lagoon 46. They sell you a Lagoon 46 and decide which hull you get closer to the date, which is why a class listing here carries no build year. Inventing one would make the page look more precise than the market actually is.
The practical consequence is worth knowing before you enquire. On a named hull you can ask about the captain by name and read reviews of that specific boat. On a class listing you are choosing a specification and an operator, and the operator is the part that varies.