No it isn't yet. I've made low fee transactions which have been prioritised over higher fee transactions recently.
i said that because i sent spent some very old coins (i think from 2014) and it took a long time with low fee (just moving from cold storage to cold storage
). but thinking about it, and what you said about those miners, i can see that may be right. because i have had 0 fee transactions mined by those miners.
If you look at the block delay estimation on
https://bitcoinfees.21.co/ there is a lower bound and an upper bound. Currently some transactions in the 1-20 sats/byte range are being confirmed after 5 blocks, where other transactions in that range might not be confirmed at all (5-Inf). 101-120 sats/byte range show 1-18 blocks delays. So some lower fee transactions are being confirmed in 6 blocks, whilst some of the higher fee transactions are taking 19 blocks.
this makes sense.
... low fee like bittrex with 20k satoshi, and get a fast confirmations on my wallet, i usually wonder how can they do this...
bittrex takes 20K fee from you buy pays 40k fee on the transaction (about 180 s/b)!
go check your tx in a block explorer and you'll see.