That's misusing the logic behind the distinction that you are raising in philosophy isn't it?
Calling an observation subjective is true in an absolute (God like) sense but if 10 people observe the sun coming up in the east, that's pretty objective. It 10 people observe a flying cow, that isn't objective. It's about probabilities and prior factual cases.
If 10 people observe the sun coming up, their observations - i.e. the experience they have upon the photons hitting their retinas etc - are subjective. But their subjective observations are of an objective phenomenon.
Science, not philosophy, works on a slightly different idea of objectivity, and is really about a "reliable intersubjectivity" (intersubjectivity is another term for "shared subjectivity").
In Philosophy
objectivity is a stricter concept, and means independent from any perspective or experience, or from any mind etc.
So in philosophy, the observation itself is subjective, but what causes it - i.e. what is emitting the photons - can be objective. The sun will be there, doing what it does, whether humans are there to observe it or not, no matter what perspective it is viewed from. It, as a phenomenon, is objective. But how we view it will always be subjective.
Science takes all those subjective viewpoints, and from them infers a reliable intersubjectivity - i.e. distils down what we're subjectively observing to reliable characteristics / properties. But note that science is nearly always examining the cause of our observation, not the observation itself. (Exceptions arise where science tries to look at the very nature of observation itself, at vision, why we "see" etc).
You say if an individual sees it, it's subjective but the fact that it is there is objective but you can't establish that fact other than with human observations and probabilities.
You can establish that there was a cause. With no cause, nothing would happen, you would observe nothing. So there has to be
something there, an objective phenomenon. Even if it is an hallucination, the cause is objective (e.g. something neurological) even if we don't understand it.
Science can help us understand the characteristics / properties of that objective phenomenon through this idea of reliable intersubjectivity. But philosophy still distinguishes between the observation (subjective) and the causal phenomenon (objective).
You can use test equipment but that's designed by humans and the data is interpreted by humans.
In science, yes, to arrive at this reliable intersubjectivity. Science calls that "objective", and will refer to it as a "scientific fact" if it is deemed sufficiently reliable, etc. But that is science, not the strict sense of philosophy.
There is a use case in philosophy for the point you are making, that being humans see patterns that sometimes aren't there, draw false conclusions, etc. But to say that it is always subjective but the fact is objective, really has no useful meaning or relevance, even in philosophy, right?
Philosophy is the realm where those distinctions are made, where they are examined. It provides the framework. Other realms (science, psychology etc) then take that and come up with the practical aspects. So to say that it "really has no useful meaning or relevance, even in philosophy", would seem to miss the point of philosophy.
It's like someone coming up with mathematics: it has no inherent use
within mathematics, does it? However, other areas (engineering, accounting etc) can make use of what mathematics defines, what it clarifies, what it examines.
