We all know about the discrepancy between relativity and quantum physics at the scale relative to particles.
No, we do not, at least those of us who have studied particle physics for decades.
Special relativity and quantum mechanics describe particle data with great accuracy. General relativity, due to the extreme weakness of the gravitational constant and the tiny masses of the particles is beyond the pale of measurements possible with particle physics .
How can this be reconciled with what are supposed to be two incompatible areas of physics?
The incompatibility your are referring to is that quantization of gravity is still at the research stage. The need for quantization of gravity appears at cosmological distances, and particularly in modeling the Big Bang. There exist effective field theories that are used in the BB model with quantization of gravity before 10^-32seconds. It is at cosmological scales that the two, general relativity and quantization have to be reconciled.
The most promising research field for quantization of gravity is with string theories, which can accomodate both General Relativity and embed the Standard Model of particle physics. Once a definitive model, based on string theories, is found even this "incompatibility" at cosmic scales will disappear.
Your misunderstanding is based on the word "macro" . Macro for general relativity is on cosmological scales. For GPS to work well we need GR, for problems like a falling apple its effect is too small to be measurable in the lab. The experiments you are talking about are not on cosmological scales.