What is the reason behind using brass for the garden hose fittings? There are several other materials that can be used.

Plastics are not usually robust enough due to which it lacks in the area of being long-lasting, although they can be used if you want inexpensive ones. Now it's very convenient to get Metric Adapters and various other tools online.

Though aluminum is corrosion-resistant yet it's not strong or corrosion-resistant enough as continued exposure to water invariably leads to corrosion. The aluminum fittings rust before the hose itself decays and likewise can gall. Aluminum fixtures have been pushing out the brass for the last several years as the cost of copper increased.

The hose producers practice embellishing gold anodize coat to the aluminum. This is a false attempt to hide the aluminum and present it as brass. You can carry a little sharpened instrument with you to the store and scratch the fittings to distinguish which have the gold-colored coating by the silvery aluminum metal that will display through the scratch. Then avoid the aluminum fittings whenever possible.

Steel fittings would rust tight in a blink. They are a poor choice.

Brass is reliable, totally corrosion-resistant, and simple to cast and machine. Although, it seems to cost more but offers a fitting that will last for the longest time and does not gall while being screwed or unscrewed.