Lock ons tree stands
 

How safe are these I mean something doesn't seem right about a stand being held on a tree by straps or am I missing something??

Yep, friction!

well as long as you don't go over there weight ratings and replace and REMOVE stand from tree as per MFG's recommendations there super safe, as per NOT breaking or coming off tree/
they use same like straps to hold cargo down on trailers and such, in tens of thousands of lbs( they make straps in all sizes more or less, just weight rated per application)

the flaws with straps , is honestly, that folks tend to LEAVE them on tree's for too long, or can get UV damaged or critter's can chew on them(never had it happen but have seen it)

MOST all tree stand makers, tell you NOT to leave stand on tree for more than like a week or so at a time, due to the tree is always growing and can apply ton's of tension, to things, and cause a failure
very few hunters remove there stands as per MFG"s instructions
most I think leave up all season??
ME< I never left lime up for more than 2-3 weeks, and I always added a second strap as a safety net of sorts, which I think is common practice among many hunters

but just cause there straps and not chains, or cable, doens't mean there weak, just have to live with the steps you need to follow to be sure there safe and used correctly!

Installed correctly they aren't going anywhere. I add extra straps or chains to treestands once setup. Compared to climbers and ladder stands I find them studier once mounted that way. I can't get any side to side movement even if I would try to force it to.

We always add a second strap also. You can never be to safe !

I use an occasional strap on my ladder stands to tighten them better against a tree, but always use chains that I can lock to secure them safely and not have to worry about theft. They also can't be chewed on by squirrels or porkys and UV light sure doesn't mess them up like it can with straps.

I've used a few of those stands. The only issue I had was the stakes I was given to use. Maybe I'll trying a climbing stick next time but the stand was secure. I did use a chain as well to keep it safe and if I wasnt gonna hunt that spot for more than a week I took I down.

Always add extra straps that are rated for a lot more than I need and after two years I replace cables
With chain and cover chain with heat shrink after painting the chain and that last for years , I prefer locons with ladder sticks over my climbers