A scanned 4473, written by hand, is just a picture, jpeg, bitmap, or tiff; it cannot be searched. Database entry is a manual operation.
Um.... They’ve had good handwriting recognition via OCR for over a decade now; acceptable recognition for almost 20 years. How do you think the IRS processes handwritten tax forms these days? I had a short term contract in an IRS processing center six years ago and even then the OCR was usually good enough to read 95% of handwritten returns.