Canva, Adobe and Vistaprint all give away a business card designer, and they are good at it. Designing the card was never where this goes wrong.
Where it goes wrong is the file. A printer needs the artwork to run 3mm past the edge on every side, because the guillotine that cuts a stack of five hundred cards moves by a fraction of a millimetre and without that margin you get a white sliver down one edge. They need crop marks showing where the cut goes. They need the text to be text rather than a picture of text. A free export from a design tool usually has none of that, so the order either comes back or gets cropped into.
So this is a card designer measured in millimetres. The preview is shown at actual physical size with the bleed and the safe area drawn on it, the check names the specific reasons a printer would send the file back, and the export is the trim size plus bleed with marks, front and back on separate pages.