That's a pretty typical design for power supplies. Transformers output depends on the mains input. Where I am this is nominally 230V, but in reality ranges from

That's a pretty typical design for power supplies. Transformers output depends on the mains input. Where I am this is nominally 230V, but in reality ranges from 235-245V. So they often use a linear regulator to obtain the required voltage, but these need to drop from a higher voltage so they choose a range that would require the least dissipation.