There are several reasons:
LOW COST: If Oz were to use aluminum or glass bottles (which are more expensive than plastic) we would need to charge a large deposit (around $5) for each bottle you purchase. You would get the deposit back when you return your bottles, however, we believe this add-on fee would still be cost prohibitive to many people. Because plastic is considerably less expensive, we simply can include a small $1.00 deposit for each product purchsed. We will refund customer accounts $1.00 per bottle upon return.
DURABLE: We have chosen HDPE (high-density polyethylene) plastic. This type of plastic can withstand temperatures up to 176 degrees Fahrenheit. This is an essential characteristic as we will sanitize our bottles with high heat in commercial dishwashers. HDPE is so durable, we believe our bottles can be sanitized and reused 100 times or more. Some reuse businesses use aluminum, however, aluminum is more fragile and can only be used between 4-10X
LIGHTWEIGHT. Heavy products, like glass, when transported have a larger carbon footprint. Light products, like HDPE, have a lighter carbon footprint.
It is proven that single-use plastic is bad for our planet. However, when you can use that plastic bottle 100 times or more, it becomes the better choice for customers and the planet.