That's a serious family tradition right there. I'd be asking them what the biggest change they've seen is, like if certain flowers got way more popular or if the bidding process went digital. Those old timers have seen the whole market shift over decades. You learn more from their stories than any guidebook.
Read an article a while back about how tulip varieties at those markets have completely changed. The old types they used to grow are mostly gone now, replaced by newer breeds that last longer in a vase.
Forty five years sounds like a long time, but is it really a tradition if it's just a job? Most family businesses don't last that long anyway. I guess it's just a guy selling flowers.