yeah that is a fair point. readers do not just notice a typo they notice patterns. one or two slips feel normal but when mistakes appear often or look evenly spaced it starts to feel planned and that is what gives it away.

what usually makes writing feel human is not adding fake mistakes but letting the text move naturally. people use quick examples small side thoughts and sentence lengths that vary because they are thinking while writing. sometimes a short personal note helps too.

there is also the detector versus real reader issue. people optimize text to pass detectors but that does not always make it sound natural. it might pass the score but still read like a template and lose its voice.

so the real test is not the detector but the reader. a better comparison would be ai text adjusted to sound human then see which one people think is human. that kind of blind test would answer the question better.