The military also trains 0 hour pilots to fly a fast jet or transport airplane with less than 250 hours of training.
That is true, but they continue AFTER the 250 hours with lots of "hands on flying", currency & supervision. After a some years/1000+ hours they will have gained invaluable experience that will come in handy the day they need it.
If you give the same training to a guy and then put him in an automated flight scenario, he will never get the same experience to fall back on.
You can do a lot in the sim, but never truely stress a person.
A cadet may first see his life in real danger during an emergency in a widebody. There is a high chance that the other categories of pilots have already experienced this before and know how they will react.
There is pro and con's for both programs. In my opinion hiring DEFO in times when the airline industry is stagnating or contracting opens a pool of qualified applicants, while having a cadet program guarantees a constant quality level of new CX pilots when the airline industry is expanding fast.
The biggest problem with Cadet programs is that there are tons of qualified pilots on the street already. When airlines decide to go for cadets versus qualified pilots the main reason is cost lowering - But at what price? Only time will tell.