Each and every colony would have had a different system whether it was their laws, taxes, railway systems, tariffs and transport, this was a problem. The transport in each colony was different such as, the railways. Many people found it hard travelling on one train and getting on another train just to cross the colony borders just because of the different rail tracks. After Federation all the railway tracks amongst the country were identical.
One of the main reasons why Federation started was to create a better, yet stronger defence force because each individual colony was not strong or big enough to protect Australia's coastline. Many colonies found it difficult to defend Australia’s coastline and so many colonies suffered by the small number of soldiers fighting and protecting Australia. So uniting Australia would have the benefit of having a large and stronger army. By this it was easier to unite as one, making it easier to control and even easier by using one command.
An important reason why Federation occurred was that the trade between the colonies got stronger which lead to better trades, telegraph lines and identical railway lines. This was one of the better ways to communicate amongst the whole of Australia. After this happened Australia's economy grew larger and stronger and then the colonies started to feel united and finally feeling like Australians.