I have had a lot of similar problems over the years. For example, phone records may include IMEI and IMSI numbers, which are 14 or 15 digits. Unless you take special care, Excel will turn these into, say, 1.234E+14, certainly losing precision on the display, and potentially in the number itself. While you can take care with your data set, you cannot be sure if everyone else is taking the same care. Someone who uses your outputs, for example. I had a similar effect with invoices numbers on another occasion. Things that happened to resemble dates got converted to dates, all the other data in the column remained as strings.

Excel is definitely not the only spreadsheet tool, but all have similar quirks in my experience. Converting what is typically pure text data (such as a CSV file) into 'typed' data is fraught with difficulties. As for people putting things like addresses into CSV format: hours for fun when one of the fields has a comma in the value. I have fought many a campaign to get people to use tab separated data instead of comma separated, with limited success.