Carpentry in feet and inches is needlessly complex. Try to calculate the distance from the end of a roof to the edge of the first of three dormers equally spaced, in a roof where the dormers and the roof itself measure some odd numbered feet/inches/fractions of an inch. (Without a pocket calculator that does fractions, obviously).
Or work out the rise/run measurements for stairs. Be sure to allow for carpet on the stairs but not on the floor of the lower level! Dividing vertical height by number of stairs is sure to result in some weird, hard to calculate fractions for each rise.
Concrete calculations considering area, depth, volume then ordering material in cubic yards takes some figuring. Base 27 mathematics???
(Once upon a time Journeyman Carpenter here, obviously pre pocket calculators).
Conversion to Metric will be gradual, particularly because building materials are in inches, but construction calculations will be simpler after we follow the rest of the world into the modern era.
The way I work around a lot of this is by rounding and erring on the side of larger. Concrete volumes are rounded up to larger numbers that are easily calculated, or square footage for heating purposes is rounded up. This gives me a worst case scenario for other errors and makes the calcs easy to do in my head. For instance, I can then easily come up with the BTUs required and know it will be enough. Areas in houses are seen as percentages of other known areas and added together. The amounts of pipe for heating is based on a factor of 1.4 lin ft. per sq ft, for instance. If sales tax in 9%, I know it's not going to be more than 10% which is simply a decimal point move in the numbers I'm working with.
Fortunately, most of what I do doesn't require extreme accuracy, like required in machining, but it does require that I'm not short on the materials or the heat delivered. To me, time is money and the less I spend on gathering raw data the better and running out of materials is expensive.
It's funny too how numbers must make sense. Extreme fractions are comical representations of size. "Hand me that 27/64th bit John". Am I expected to divide an inch into 64 equal pieces and then gather up 27 of them to understand the size? As with the rounding for finding the materials needed, the rounding for pricing is also valid. Would you charge someone $6,127.87 for a remodel job? Or just tell them $5,900.? Which is more easily understood and which sounds better? The number 6 is more painful than the number 5, but the amounts are virtually the same. You see this all the time in car sales. "Drive this baby home for $29,999. No! it's not $30,000!
I used to be kidded for doing bids in my head on the spur of the moment, so I began to deliberately wait a couple of days to give the price, even though I knew all that time what it was. When I could not decide on the final price, I'd dial their number and decide while it was ringing what it would be, or wait until I heard their attitude during the call. Nicer gets a lower number, not worried about a budget gets a higher number, etc.
So percentages and perceptions play a large roll. Percentages, like in sizes and amounts, make calculations much easier than exact numbers, while allowing a fudge factor for errors. Perceptions form the relationships required to be successful. Perceptions permit and mandate the amounts being discussed. They are the basis for the response from the customer. In a sense, percentages are Metric.
Your bidding example shows Metric IS more natural, intuitive.
