Not only do some people think Australian plants can be neglected, they also expect them to live forever just because they have a reputation for hardiness. As with many exotics, certain Australian plants only perform well for a limited period of time.
Some shrubs and trees may have a fairly long life but some herbaceous perennials should be regarded as short-term items, to be replaced periodically. Red and green kangaroo paw (Anigozanthos manglesii), for example, is best treated as an annual. Hybrid kangaroo paws may last three or four years, after which their best performance is over. Lechenaultias also should be replaced after a year or two when they have lost their looks.
Be aware that over-watering and over-fertilising may shorten the life of Australian plants. They belong to an ancient flora that has never relied on outside help, and you can kill them with kindness by forcing them to grow at an unnatural rate, causing them to reach maturity - and old age - too soon.