Why are zero fee transactions not being included in blocks that are not full?

[Bitcoin]

Why are zero fee transactions not being included in blocks that are not full?

Today, I sent a Bitcoin payment but it has not been included in a block for about 10 hours now. The payment had the following characteristics:

• ~0.1 BTC


• 222 bytes


• One UTXO as an input (I used coin control)


• The UTXO was approximately 1 year old

Currently, blocks are not always full (in fact there are blocks that are only 8% full). For that reason I attempted to save the fee.

(https://bitcoinfees.github.io/#1m)

(https://blockchain.info/ 2016-08-08 20:42 UTC).

What policy do miners currently have regarding zero fee transactions? I have sent many zero fee transactions in the past (>1 year ago) and the block inclusion time was really quick (~5 blocks maybe). Did the policy of miners change?

Source: Why are zero fee transactions not being included in blocks that are not full?