Thought I'd try a gopro the other day. I first recorded 45 minutes of our kit riding in the car boot and then when I thought I'd turned it on for a game I'd turned it off. Did that all day and got nothing but the bench in the safe zone... lol
You aren’t the first person and won’t be the last
You've got a point. And it says "no trainers allowed". Not "no sandals" or "no novelty oversized clown shoes" or "no traditional dutch clogs" or even "no diving flippers"
I did play a vietnam themed scenario once in British Army issue flip flops/sandals.
No one cared*, other than the many comments I overheard “that guys playing in a T-shirt and sandals”
* not entirely true, I immediately regretted it as I arrived on field picking up grit and twigs between my feet and the sandals. But I was committed and wasn’t walking back to the campsite
Other than that I always recommend good supportive footwear appropriate to the environment, and I’m a firm believer in “do as I say, not as I do”
With regards to waivers there is a balance between duty of care and not letting people go on field with inappropriate footwear, clothing, PPE etc. Responsibilty cannot be offset just with a waiver.
A waiver pretty much just says that the player understands the appropriate risks of the activity and will comply with instructions.
Sites need to have appropriate insurance (covering liability to staff and customers) some is mandated and some is recommended. Such policy’s are based on risk assessments and mitigation’s.
Disallowing flipflops is a mitigation, there is a danger of not fully understanding the implications of mitigation as well as the underlying risk