Much of the equipment in the military is now computerized. The length of time in training now and the training in the military is limited.
When I and my brothers were in the service in the 1970's, we were in electronics schools for years.
Now, they teach you very limited skills and the training is sparse. This follows the trend of replace and discard. Imagine having a first termer working on computer hardware by themselves. Even when I was in, the trend was black boxes and depot level repair. Remove and ship. The trick was keeping backups on hand.