It isn't an excuse. It's true. You do need to be aware.
It's common courtesy, and they definitely should ping, but at the end of the day, it definitely isn't their fault if you get caught out and they did not ping. It's information that /was also available to you/. Just because they did not pass it along as they should have does not mean that you are not at fault.
If I had to put a percentage on it, I would split it 60/40%, with 60% belonging to you for being unaware and 40% on them for forgetting to ping.
There are plenty of reasons why they might not ping it. They might forget, they might be laning against something like Talon or Ekko who have a habit of leaving the fog of war to parkour/Parallel Convergence onto you, or a Xerath that hangs back so far they aren't visible most of the time.
The other thing is that half of the time that I get yelled at for not pinging MIA...the enemy walks past MULTIPLE wards.
Don't place them if you aren't even going to USE the wards. Do not make it my burden to constantly report everything on the map.