They could be.
Industrial engines like these run for thousands or hours with nothing but fuel. Car and Truck engines use a lot of the same technology and get close. You can have performance and long service and reliability, it's all about materials and the size of some components.
The only thing stopping the bike makers is the market. Would you buy a new bike because it has 15000 mile service intervals and does 90 mpg? Would you still buy it if it was £1000 more than the competition? Would you buy it if it was 10 mph slower than the competition? The car market broke the cost/performance barrier because the likes of Proton came in and offered long hassle free warranties and free servicing. Their cars improved to the point where people in other dealers and selling to the fleets knew they had to take the hit because if both cars are the same you start looking at the less glamorous features like the hassle of getting the oil done. They passed the info up the line and the manufacturers responded.
There is no impetus in the bike market for anything except styling and performance. It's better if your 3 year old CZX999RS is an unreliable POJ because then Mrs. Weekendrider will understand when you spend £9000 less trade in on a new CZX1001RRS. Even BMW have got their heads round it now, having people saying a 1991 R80GS is the ultimate long range tool isn't good for business when Harley can bore out the motor by 10mm and sell truck loads.
The best one was the Bonneville service interval. My first service book said 4000 mile oil changes. A few weeks after Harley launched a new 883 I got a little package from Hinkley with my new 6000 mile book. No engineering changes required

Andy