Many people love to use custom cabinet makers. for many architects, designers and builder's custom-made cabinetry is the most convenient way to go, and for homeowners the word “custom” is synonymous with luxurious or high end. However, in reality using a custom-made cabinetry is often quite risky and usually not such great value. That's because large industrial factories can use their power to develop and engineer various features which cannot be made by a custom cabinet maker. Another advantage of large factories is the consistency and quality control. For instance, it's very difficult for a smaller shop to make cabinets who are truly handles with continuance grip rails to match the cabinets. European factories normally build in all the lighting but if you are to use a custom cabinet maker you need to specify which light fixture to use, where will the wiring go, how to make the cutouts for the lighting which transformers to use etc.
Another challenge is the lacquering which normally would be done by a cabinet maker manually in a spray booth, if you will ever need to re-order a part or a door the color may not be exactly the same as one which was made using factory precision lacquering.
Most custom cabinet makers are individuals, so relying on a single human being vs an established factory is always riskier, but off course those who use custom cabinet makers are ok with it because the custom cabinet maker can take all the components which in theory are similar to what you would get from the factory and make a comparable product.
That's just like going to your local mechanic and asking them to figure out what all the components of a brand-new Mercedes are and build a better car. In theory it is possible in our days with the power of the internet but most of us would not do that because we trust the industrial power of Mercedes, their RD department and their quality control, safety testing etc. since most people would not want to risk their safety when driving on the highway to their local mechanic. If this is true for cars, why wouldn't it be true for kitchens?
Kitchens are very mechanical and it is very important to make sure they function well for a long time. Usually you would open and close your cutlery drawers' tens of thousands of times during the lifetime of your kitchen so just like a good reliable car you would want your cutlery drawer as well as your entire kitchen to function properly forever.