Water at concerts

So a few weeks ago, I was at a concert. It was outdoors, just outside of Perth. It was a hot, hot afternoon with little to no shade. The sun was so hot, I felt like a roast chook in an oven (I was actually wearing mesh at the time lol).

Outside the venue, security guards were ordering people to tip out their water bottles.

Inside, they were offering $5 for one bottle of water.

Regular vending machines and shops sell them for $2.80 - $3.50. Generally, if it’s more than $3.80 it’s ridiculous.

I didn’t see anyone affected, but people could have experienced dehydration and/or heat stroke.

My questions are:

1. Should it be legal for venues to do this?

2. Is someone did suffer a heat related illness/injury, do you think the venue would have been breaching their duty of care?

((I’m actually going to bed now so I will check responses in the morning))