It doesn't take into account the buying power of money at the time. The 70's you could buy candy bars for a a quarter and tickets are say $2.50.
Now its $1.50 for a candy bar and $7.50 for a ticket.
Example A tickets are 10x candy. Example B tickets are more than 4x candy..
Inflation is supposed to account for the difference in the buying power of the currency. And factors like the examples above, population, demand, etc should be taken into account as they are in various indices from the widely used CPI and even down to the tastier Big Mac Index.
Hence price now vs price then = lazy.....when using the term inflation.
Now, if people just use it as a comparison point....cool. But it doesn't really count for inflation.