This is only the latest example that I have seen where plumbers and electricians butcher the structure to put their stuff in.
In new construction I blame the framing crews and /or the architects. They
know where the tub is going and the architect should spec the floor joist lay-out to accommodate the drain plumbing. If the architect doesn't spec it right then the builder should catch it and fix the problem. Everyone should be thinking through the building process rather than acting like automatons fulfilling pre-programmed tasks. I've done enough of every trade to understand the plumber's frustration when arriving at the site he or she observes no provision was made for waste plumbing. It makes you want to go to the van and get a chainsaw.
I remember a few months ago seeing a TJI completely cut in two where the plumber cut it to install his drainpipe below a huge whirlpool tub. Large load (tub full of water and two overweight Americans) + no floor joist = trouble.
That's not quite accurate. The human body is just barely more dense than water. If our lungs are full of air we're slightly less dense. So, the tub weighs approximately the same whether it's filled with water or fat people; you can't fill it with both. ie, fat people displace water and so when they get out there's about a gallon left in tub.