In the online lesson on Processing Weekly Donations
, on slide 23, it says "Only the bishop and his counselors may receive donations."
Now you may think that this just leads right back to your original question, since one could substitute "donations" for "tithes and offerings" and the question would be the same. However, that lesson refers to "donations" whenever it talks about money received and processed. It never uses any other term, which implies quite strongly that the process that is being documented is one that applies to all funds received. So I think it is safe to conclude that these principles apply to all money that is handled, whether it be tithing, or missionary funds, or camp payments.
You raise a good point when you say, "For example, may the Scout Committee collect the Scout Camp payments before turning them over to the ward? I can think of several excellent reasons why they should avoid the practice...." My stake presidency has taken the position that all the principles that lead us to safeguard tithing should be followed in handling any moneys given to the Church. All such donations/payments/whatever should be given to a member of the bishopric in a sealed envelope, and processed with the regular donation batch. That safeguards everyone involved in the process.
I wish the documentation were clearer, but it is my personal opinion that the references to "donations" and "offerings" do indeed apply to all funds handled by the ward and stake. And my stake presidency agrees. I can imagine that other stakes might have a more relaxed policy, which is within the authority of those stake presidents to decide.
Please don't ask me questions via PM that can benefit the larger community.