Just had a custom home completed, and walked thru many in different stages of build from the same custom builder. My home is all wood plank tile, no carpets. It was laid before cabinetry and baseboards so its under all of the cabinetry, it looks perfect, no gaps . Im not sure why there would be. Went thru other homes that the tile was put down to where it looked like the layout for the cabinets would be, but underneath wasnt completely tiled. The tilers do take into account where the appliances slide in and tile those areas. I cant imagine a new home built with appliances tiled in. I never saw tile butted up to any cabinets. In my opinion, its normal to not have tile completely under your cabinets, but i think that its perferable to have flooring run under your vanities and kitchen cabinets in case you need or want to replace with something of a different size. An example would be replacing a vanity for a smaller one or one with legs, or at some point redesigning an island, you wouldnt have to match (almost impossible) or replace the flooring. If you have a choice and its in the budget, tile the entire floor (IMO). We didnt request a full floor lay, I think that it came down to when the materials were delivered, and keeping the subcontractors on schedule. Good luck w your build.
ETA If you have any questions or concerns about your build, have a meeting with your builder or whomever is managing your build. Dont waste your time here when they can answer questions about your particular concerns. All anybody can throw out here are their own experiences and opinions.
Q