What other brand has given customers free upgrades after purchase? Just Tesla. Why would you expect them to include these things in already-sold vehicles? FSD will work as-is, the additional hardware/upgrades will make it work better, but won't prevent it from working without those things.
Because when many people ordered their cars months before - they ordered them expecting to receive Ultrasonic sensors.
These sensors helped with parking and the smart summon feature.
Then Tesla decided to remove these sensors - before they had figured out how to replace their function with software!
The only information that Tesla gave was that this functionality would arrive sometime in the future - we are now 4 months down the line with no software update in sight.
Tesla have already offered “free“ upgrades of HW computers & cameras to buyers of earlier models - so it is not without precedent.
If the current hardware on cars without USS will not be able to replace those functions with current cameras and new software - I would expect Tesla to retrofit something that will then make them work - as they were ordered by the customers.
Don’t forget - other car manufacturers have faced supply shortages and have given customers refunds for items they have not been able to supply - Tesla did not offer customers any refund for these missing sensors - just some vague promise of software in the future!