The Perseus is really new, it doesnt have much service time since it was introduced on the end of the conflict. The Eryines was only in service with the SOC but it seemed to be on opeval with them, it was only much later that it was deployed for the fleet. The bombers are also new but its said in the techroom that all Artemis are serving with the 2nd and 3rd battle groups and the Boanerges have been assigned to elite bomber squadrons in the 3rd, 4th, and 5th Terran battle groups so that seems to show that there are only limited number of these craft. It would appear that most of the fighters and bombers that the GTVA were using before the game were the Herc IIs, Myrmidons, Zeus and to some good extent older crafts. They lacked Hecates because there doesnt seem to be many of them around, my guess is that the ship is a even newer desgin then the Deimos and because it takes more time to build a destroyer there shouldnt be too many of them (we only see 2 on the main campaign).
About the Vasudans tech level, it would seem that all of their ships (except the Ptah) have already been in service for a good time.