In England in 2015, Cameron had 40.9% apparently (https://www.statista.com/statistics/717022/general-elections...). The point still stands—he had far more than 40.9% of English seats!

On the other hand, the Turkish electoral system can fail even more bizarrely than a simple single-member constituency FPTP system—in 2002, only the CHP and AKP cleared the 10% threshold, so the AKP had ⅔ of the votes.

However, at the moment, the president is directly elected, so anything <50% wouldn’t suffice. (How those votes are obtained, of course, is another matter.)

That's actual voters of course, a subset of how many people support a candidate or President in the US. The parent has no idea how many people support Erdogan (the claimed 50%), nobody does. It's just a guess in the wind (if it's 42% that's a massive difference from 54%, as to whether Erdogan remains standing). Like trying to guess how many Russians really support Putin's dictatorship. Getting honest answers on such questions is quite difficult, as is accurately polling in nations the size and complexity of eg the US, Russia or Turkey.