Why can't states opposed to farm laws be allowed to accept them later?

If eight states could join the VAT system after the rollout date, why can't the same apply to states opposed to farm laws?

Many theories on how the farmers’ agitation went astray on the Republic Day are doing the rounds. With clear signs of the two-month long agitation by farmers losing momentum without a road map on the direction of its future course, a post-mortem examination is also going on to find out why and how the situation came to such a pass as it has now.

One of the popular theories gaining salience in many debates in the media and elsewhere suggests that the farmers made a tactical mistake by not accepting the government offer of keeping in abeyance the three new