Your post whilst strictly factual, is misleading and not addressing anything whats been posted.
Ever looked at a chassis? You'll find they are full of holes already.
As far as i'm aware anything less than about 3.5Ton gross vehicle weight does not have a chassis. They are monoqouque construction, which is basicaslly the vehicle body strength is all in the shell, albeit with some additional ribbing. Drilling into, squashing or clamping this ribbing compromises the integrity of it.
If you're refering to holes already pre drilled into conventional chassis, i.e 3.5T tranny van, they are usually there for a purpose. I.e modification to uprated suspension, tipper body, luton body etc.
Ratchet straps are useless if the rings aren't rated at least the same or above. No point having a 5 tonne strap on a noodle welded to the wheel arch (as my dispatch was).
You'll find that load lashing points do indeed meet the vehicles saftey criteria. Although if someone chooses to fit say.....an upright tank near the bulkhead and secure this (which is probably somewhere near the total payload) then indeed just using a few of the lashing points may not really suffice.
I've said it before and i'll say it again, the current marketting blurb from any tank/frame/manufacturers/fitters/crash testers all focuses on one thing..........the tank frame retains its integrity in an accident. Totally rips the arse out you're van, but the frames fine. They all follow a bolt through the floor method. Its archaic, crap and a case of following what everyone else has done. The tanks need securing in the vehicle other than bolting through the floor, its very easy to do and a lot safer and it doesn't trash your van in a shunt.
The current crash test videos all compare a floor bolted weak frame giving way in an sudden stop, the they show the same thing with their "safe frame" ripping out a floor, but staying intact. So thats it, there only them two options? Don't think so.
But like everything, people are selective in what they want to see. Often Dave you shudder at people with home made tanks, gas heaters etc.. and think nothing of flouting a 20mph saftey limit? We all have our own standards eh? Of course i'm sure that YOU personally will be fine driving at 40mph through a 20mph limit with a saftey water tank fitted, even though your insurance have deemed you high risk and bumped your premium that you complained about. Wasn't your fault though? I get that.
And if anyones further interested in vehicle fluid tanks and saftey, go check out any artics 450 litre diesel tank on the side of it and see how its secured. I've never heard of one coming off and hurting anyone. Looks to me like two metal bands and four small bolts. but eh, what do i know !!