If you don't live in a country with dumbass analogue laws and "emergency bans", RC's are hugely advantageous over "street drugs". Granted you have a good source (ie. who can provide lab analysis proof of the purity of their product), you're getting EXTREMELY high purity product (which is very rare on the streets) delivered straight to your letter box.
Once you have one or several reliable sources, you're 99.9% insured you will get your product: when was the last time your coke dealer gave you an 8 ball for free, because the cops busted you with the one they had just sold ya.
I've allways got 1 gram of x or y RC, not 0.8g's from a street dealer "yeah but it's coz it's really high grade stuff....8)"
9 times out of 10 when ordering RC's, if you plan a little in advance, you're sure to have your stuff in time for whatever event... With street drugs, unless you have a direct connect, you have to ask a friend to ask a friend etc. or worse, go cop in the hood, likely not get your drugs in time and or get swindled, jumped, robbed, arrested...
However because of the repression in certain countries, potentially very dangerous RC's are out there, created to bypass a ban on it's "parent compound"... "Good" sources do not carry these though IME... If you're in one of the more tolerant countries, you can still get descent RC's legally, so it's not a criminal/judicial issue as it is with "street drugs".
i could go on....