BinaryReader vs byte[]+shifts

Question

I must be misunderstanding what BinaryReader is doing. Why are these outputs different?

{
    var data = File.ReadAllBytes(testFile);
    var pos = 0;
    var read8 = new Func<uint>(() => data[pos++]);
    var read32 = new Func<uint>(() => (read8() << 24) | (read8() << 16) | (read8() << 8) | read8());

    Console.WriteLine(read32());
}

using (var reader = new BinaryReader(File.Open(testFile, FileMode.Open)))
{
    Console.WriteLine(reader.ReadUInt32());
}

Answer 1

Endiannes.

Use:

var read32 = new Func<uint>(() => (read8() | (read8() << 8) | (read8() << 16) | read8() << 24));

On a side note, please don't write code with such side effects.
You are getting away with them here because the order of evaluation is guaranteed, but still please don't.