Its not just a Hamilton problem, it extends to essentially all councils, everywhere. They have increasing compliance and service costs but since the reforms in the 80s have realistically only had rates as a way of generating revenue to pay for things. That’s one of the reasons why Three Waters was happening; it was an acknowledgement that there was no way councils could pay for necessary improvements so instead of expecting them to fail, it would be more centralised and allow government to fund it.

Have a look at the graph Fig 6 in this study which shows how funding for local councils changed over time. https://oag.parliament.nz/2014/assets/part3.htm

Of course, the services they provided changed as well - they weren’t responsible for power, but the cost to the end user just shifted from going to a council to going to increasingly privatised lines companies etc.