A couple of years ago on reddit, someone issued a challenge to find the destination of their private Zcash transaction. Someone won the challenege, not by tracing the transaction itself, but by recognizing it was the only transparent to private, and private to transparent transactions with in a timeframe. That's why privacy needs to be mandatory like it is with Monero.
This is quite outdated, I believe. With the launch of NU5/Halo2 in a couple of weeks, all transactions will be private by default. Plus, even without that change, the shielded pool is way larger these days. Finally, a fairer comparison with Monero would have been to trace a shielded to shielded transaction. This should be literally impossible with Zcash.
Private transactions by default sounds good, glad to hear. I guess that's why they extended their 20% dev tax past the initial first half of emittance like they originally advertised.
