All that "transformer" does is maintains the line impedance at 75 ohms and matches the input to the output. A standard splitter will have this in it. The better quality ones we have here in NZ have MOV's. Don't forget also that there is often a power-pass feature for line-powering devices, this means that a diode is often included for reverse polarity protection.
Let's face it, these days if you're not young, you're old - Red Green