I agree. The bridge structure is well reinforced, the Russians foresaw the danger of hitting its supports, and to avoid such incidents they must have installed special bollards made of reinforced concrete, sheet piles and stones.Most likelly the CIA had information about the equipment they used to detect explosive, and a group of engineers had overtime somwehere in the USA to find ways to hide explosive device from it.
Only way to stop this kind of attacks is to increase the cost of the USA to do so .
Which forecast incteresting options for Russia.
The only question now is how much it will cost and how long it will take for the repair to complete, and I highly doubt Ukraine will stop now. Attacking the Crimean bridge was always a considerable desire to humiliate the Russian political and military leadership, now they have succeeded, in addition to impacting on the logistical reinforcement of Kherson and Zaporizhzhya.
Kherson will fall perhaps even before the 15th of November.