Just came back from a stay at The Royal Sands. We are both vaccinated. Every precaution seemed to be taken. There was a girl on my flight from lax that kept taking her mask off. The staff reminded her several times and ultimately gave her a "final notice" and had her sign something. (I don't know what this means......but seemed serious to me...) There is someone at every business entrance with sanitizer. Masks were worn by almost everyone. We went on a day trip to Chichen Itza and masks were required. The bus driver delivered a shot of sanitizer before boarding the bus. There are even mats before entrances to sanitize shoes. I didn't know about any of the staff's vaccination status, but again, everyone had a mask. The resort provided Covid testing, which was very convenient but there are even drive-thru testing sites in the hotel zone. I live in Southern California and feel that people here are generally careful, but I felt that- in Cancun, they are over-the-top careful.
Additionally, the security at the airport seemed more strict than ever. They especially focused on electronics and liquids greater that 100ml. (I had to toss my new bottle of hot sauce! It was 145ml....)
So ultimately, we were probably safer in Cancun than in Southern California.
And darn. Wish I would have bought a bottle of Kahlua and checked my bag...