Yeah - that 3/4" is a radical tilt! If anything it should tilt in just a tiny bit.
Most tubs will allow a tiny inward tilt (to avoid water running out and onto the floor) and still have good drainage from around the edges, and some have a nicely sloped rail and shelf area that drains water great even if the tub is out of level a bit. It seems a 3/4" tilt would be enough to allow water to run off the tub onto the floor ..
It is wierd for a cast iron to be so far out as they usually have molded feet underneath (so if the floor was perfectly level the tub would be, too.) If anything was used to shim the feet (as should be done), it should have been done to correct the out-of-level floor- not make it worse! Wierd ~~
When you check the level, are you resting the level on the top of the tile flange (well, that little ridge) and spanning across to the rail? That little ridge is not very tall, but maybe about 3/4 ", so I wonder