Because they don't need to. Simple as that.
I mean, I’d argue there’s a pretty big shortage of up-to-date cars in both road (economy and sports/exotic) and the main racing categories. Big offenders being Ferrari and BMW, which are about to be 2 iterations old, with the 458’s successor about to be replaced by the 296, and the M4 being the current GT platform IRL, which succeeded the M8, which succeeded the M6 we’re still currently operating with. These would seem like they’d still be important with GT7 still carrying on Sport’s esports and competitive modes, which make majority use of the main racing categories.
Ignoring pure fantasy entries:
Aston Martin: Gr. 3 is 10+ years old, and has been succeeded.
Audi: Gr. 3 up to date, but there’s a GT4 R8 in it’s 3rd year of racing now.
BMW: As mentioned, 2 iterations behind, but also the M4 Gr. 4 car is based on a fairly old platform.
Chevy: C8 Corvette is now in it’s 3rd year of racing.
Dodge: “Up to date”, however they haven’t been making new GT race cars.
Ford: Sport launched over a year and a half after the new GTLM started racing, and left us with a fantasy Mustang - and then introduced the 2005 GT
after the modern car stopped racing, which only got added with the launch of 7. So “up to date”, but very late to be so and no longer accurate.
Honda: Up to date.
Lamborghini: The Huracan is about to receive it’s 2nd update over the iteration we have.
Lexus: Up to date.
Mclaren: They now operate with the 720 in GT3, and 570 in GT4, and have so for at least four years. We still have only the 650 in both.
Mercedes: GR. 3 fairly up to date, but we’re still running the SLS in Gr. 4.
Nissan: The GTR GT3 is nearly 10 years old, and was raced to at least 2018, and no Z platform was ever represented.
Porsche: Gr. 3 is a generation old.
Renault/Alpine: An A110 GT4 has been around for 4 years, and it’s not like PD hasn’t already added more fictional race cars to expand the manufactures cup (Genesis and Suzuki).
Subaru: BRZ GT300 actually makes this up to date.
Toyota: A lot of asterisks here, with the GR. 4 being a fictional creation when an actual GT4 existed, and the GR. 3 being a concept. There’s still Supra variants running in Super GT, but with seemingly a lot of new real world GT cars coming up from the brand I feel like I can give this one a pass.
There’s a lot of things that need fixing in this game, but I don’t know why the people responsible for squashing bugs, adjusting economy balance, adding events, or making tracks would be slowing down the car department. At this rate there’d only be 36 cars added by March 2023, and we got nearly that many in the first 3 months of GT Sport.
I’m more confused than anything.